Working Dir errors if dir exists, but no details.

[ryanramage]

This does not happen very oft. But there can be cases if someone deletes the .details file in the module working dir, things go badly. Example:

https://gist.github.com/mandric/ea2734c73d276fadbfbf
vm@toaster:~$ cat /srv/storage/gardener/logs/startup.log | head -100
info: [gardener] polling couch for design doc changes.
info: [gardener] watching db dashboard for new installations/updates.
info: [gardener] Scanning design docs on _replicator
info: [gardener] Scanning design docs on _users
info: [gardener] Scanning design docs on dashboard
info: [gardener] polling couch for design doc changes.
info: [gardener] Scanning design docs on _replicator
info: [gardener] Scanning design docs on _users
info: [gardener] Scanning design docs on dashboard
info: [gardener] polling couch for design doc changes.
info: [gardener] Scanning design docs on _replicator
info: [gardener] Scanning design docs on _users
info: [gardener] Scanning design docs on dashboard
info: [gardener] polling couch for design doc changes.
info: [gardener] Scanning design docs on _replicator
info: [gardener] Scanning design docs on _users
info: [gardener] Scanning design docs on dashboard
info: [gardener] polling couch for design doc changes.
info: [gardener] Scanning design docs on _replicator
info: [gardener] Scanning design docs on _users
info: [gardener] Scanning design docs on dashboard
info: [gardener] polling couch for design doc changes.
info: [gardener] Scanning design docs on _replicator
info: [gardener] Scanning design docs on _users
info: [gardener] Scanning design docs on dashboard
info: [gardener] polling couch for design doc changes.
info: [gardener] Scanning design docs on _replicator
info: [gardener] Scanning design docs on _users
info: [gardener] Scanning design docs on dashboard
info: [gardener] polling couch for design doc changes.
info: [gardener] Scanning design docs on _replicator
info: [gardener] Scanning design docs on _users
info: [gardener] Scanning design docs on dashboard
info: [gardener] Scanning design docs on kujua-base
info: [gardener] installing kujua-sentinel-0.0.1.tgz ddoc_url=http://service:******@localhost:5984/kujua-base/_design/kujua-base, db_url=http://service:******@localhost:5984/kujua-base
info: [gardener] Checking if module kujua-sentinel-0.0.1.tgz needs to be stopped
npm http GET http://service:****@localhost:5984/kujua-base/_design/kujua-base/kujua-sentinel-0.0.1.tgz
npm http 200 http://service:*****@localhost:5984/kujua-base/_design/kujua-base/kujua-sentinel-0.0.1.tgz
info: [gardener] installing kujua-sentinel-0.0.1.tgz ddoc_url=http://service:******@localhost:5984/kujua-base/_design/kujua-base, db_url=http://service:******@localhost:5984/kujua-base
info: [gardener] Checking if module kujua-sentinel-0.0.1.tgz needs to be stopped

/srv/software/gardener/v1.0.0/node_modules/gardener/node_modules/npm/node_modules/lockfile/lockfile.js:30
    throw er
          ^
TypeError: Cannot read property 'length' of undefined
    at /srv/software/gardener/v1.0.0/node_modules/gardener/lib/npm.js:28:21
    at save (/srv/software/gardener/v1.0.0/node_modules/gardener/node_modules/npm/lib/install.js:311:12)
    at /srv/software/gardener/v1.0.0/node_modules/gardener/node_modules/npm/lib/install.js:97:7
    at /srv/software/gardener/v1.0.0/node_modules/gardener/node_modules/npm/lib/install.js:184:5
    at /srv/software/gardener/v1.0.0/node_modules/gardener/node_modules/npm/node_modules/read-installed/read-installed.js:118:5
    at /srv/software/gardener/v1.0.0/node_modules/gardener/node_modules/npm/node_modules/read-installed/read-installed.js:232:14
    at asyncMap (/srv/software/gardener/v1.0.0/node_modules/gardener/node_modules/npm/node_modules/slide/lib/async-map.js:27:18)
    at next (/srv/software/gardener/v1.0.0/node_modules/gardener/node_modules/npm/node_modules/read-installed/read-installed.js:198:5)
    at /srv/software/gardener/v1.0.0/node_modules/gardener/node_modules/npm/node_modules/read-installed/read-installed.js:155:7
    at LOOP (fs.js:1356:14)
{ [Error: ENOENT, open 'working_dir/aHR0cDovL2xvY2FsaG9zdDo1OTg0L2t1anVhLWJhc2UvX2Rlc2lnbi9rdWp1YS1iYXNl/.details']
  errno: 34,
  code: 'ENOENT',
  path: 'working_dir/aHR0cDovL2xvY2FsaG9zdDo1OTg0L2t1anVhLWJhc2UvX2Rlc2lnbi9rdWp1YS1iYXNl/.details' }
{ [Error: ENOENT, open 'working_dir/aHR0cDovL2xvY2FsaG9zdDo1OTg0L2t1anVhLWJhc2UvX2Rlc2lnbi9rdWp1YS1iYXNl/.details']
  errno: 34,
  code: 'ENOENT',
  path: 'working_dir/aHR0cDovL2xvY2FsaG9zdDo1OTg0L2t1anVhLWJhc2UvX2Rlc2lnbi9rdWp1YS1iYXNl/.details' }
{ [Error: ENOENT, open 'working_dir/aHR0cDovL2xvY2FsaG9zdDo1OTg0L2t1anVhLWJhc2UvX2Rlc2lnbi9rdWp1YS1iYXNl/.details']
  errno: 34,
  code: 'ENOENT',
  path: 'working_dir/aHR0cDovL2xvY2FsaG9zdDo1OTg0L2t1anVhLWJhc2UvX2Rlc2lnbi9rdWp1YS1iYXNl/.details' }
{ [Error: ENOENT, o