Took out removal of existing gem sources

Tested the behavior with multiple sources. You end up with a warning if failure to pull from a source.  Appears to try sequentially, so the deterministic order from this PR would be

try rightscales ruby source
try rubygems as secondary source

``WARNING:  Unable to pull data from 'https://bobbins.com/': no such name (https://bobbins.com/latest_specs.4.8.gz)``