Add Automated Builds for Acceptance Tests via AppVeyor

[tknerr]

AppVeyor is sweet :-)
https://ci.appveyor.com

[tknerr]

It's actually running there for a while, but I still did not get reliable builds out of it.

• rake test should be doable
• rake acceptance in theory too, but on azure workers it won't run due to the 30 minutes limit and on hyperv vagrant/virtualbox vms produced random failures

[tknerr]

See also:
http://help.appveyor.com/discussions/problems/1247-vagrant-not-working-inside-appveyor
http://help.appveyor.com/discussions/suggestions/519-pre-install-vagrant-and-virtualbox-on-build-workers