Fix HTTP gem source

o Fix the following warning:

The source :rubygems is deprecated because HTTP requests are insecure.
Please change your source to 'https://rubygems.org' if possible, or 'http://rubygems.org' if not.
Add help command to UI.

o Add utility to get the gem's lib dir
o Add help document
o Help commands now opens help document in a pager
Updated README

o Tested on 2.0.0