Add Ruby 2.1.0 to Travis CI config
Add workaround for rubygems/rubygems#763

This defect in Rubygems 2.2.0 breaks all 1.8.x builds on Travis CI.

Workaround until the fix is deployed is to pin builds to latest 2.1.x
build of Rubygems.
Merge pull request #11 from ms-ati/add-workaround-for-rubygems-issue-763-on-travis

Add workaround for rubygems/rubygems#763