Do not overwrite /etc/vmchecker files on setup.py install

[valenting]

config.list and ldap.config are overwritten when deploying an updated version
setup.py should at least make a backup

[valenting]

A simple entry is needed in setup.py to copy files from /etc/vmchecker/ldap.config to /etc/vmchecker/ldap.config.bak (for example), and the same for config.list