add spec tests, lint cleanup

I need to enhance my postfix module and rather than do that and have another postfix module on the forge I would like to reuse/improve an existing one and help with the cleanup. 

A few questions:
Do you want to maintain EL5 compatibility?
OK to break out the non-postfix stuff into their own modules? (I'll move them to you in GH)
OK to add puppetlabs-stdlib as a dependency for the anchor pattern?

This commit:
Added spec tests
Added travis-ci integration (if you use travis - free for OSS)
Minor lint cleanup