Remove other OS options

Other operating systems have not yet been tested with additional direct
commands (/usr/sbin/service for example).  Also, other operating systems
have not been tested with puppet-gitlab.  Once these issues are taken
care of, I will readd the support.
Remove outdated examples

Example files need to be rewritten for LDAP and pgsql.
Update for new gitlab_requirements
Merge pull request #4 from atomaka/feature/gitlab_requirements

Update for complete functionality