Integration tests for issue #1

https://github.com/maestrodev/puppet-jenkins/issues/1

Setups up the tests plugin.pp with a vagrant file.  Adds an exec invocation which checks to make sure that ~jenkins equals /var/lib/jenkins.  


Note if you uncomment the init.pp test the problem goes away.  

I initially intended to send you a fix for the problem.  But I couldn't decide what the best approach was.

1) jenkins:plugin already depends on jenkins, move user create to jenkins and configure its home directory correctly
2) Configure home directory correctly in jenkins::plugin
3) If the user doesn't exist then there will be far greater problems, no need to try and create the user.  Delete the lines and let the rpm init scripts suffice.