Convert puppet version requirements

Checks puppet requirement to see if it is pessimistic (1.2.x) or a range
(>=3.0.0 <4.0.0) and converts them to their respective rubygems
requirement (~> 1.2 and ['>= 3.0.0', '<4.0.0'] respectively).
Merge pull request #87 from ecbypi/convert-version-requirements

Convert puppet version requirements to rubygems format