include puppet-lint in the bundle and rake tasks
disable lint check for single quoted variables

Previously we weren't linting, there's a number of warning but there was
only one actual error reported when linting was enabled.  It was
erroring on a valid usage of a single quoted variable-like string.
To allow linting to succeed (and the warning to show themselves) I've
disable the check that is giving a false positive.
allow specifying gem source via env var
put disabled checks in .puppet-lint.rc for non rake usage
Merge pull request #220 from justinstoller/puppet_lint

Use Puppet lint and ignore its warnings?
Merge pull request #219 from justinstoller/gemsource

allow specifying gem source via env var