Fixes #19 - Use List instead of CVer

This closes #20 (it supersedes and includes commits from it).

Without this fix the provider will continue to return packages that have a name ending in .number to erroneously be part of the version instead of part of the name. This also speeds up the provider and prefetch considerably as the call to `choco list -lo` is much faster than the call to `choco cver all -lo`


This also contains several maintenance changes, including using existing puppet instead of installing gem if environment variable is defined, removing the erroneous "Reading" package that shows up due to "Reading environment variables" output that comes at the end of all choco commands right now.