Enable testing for ruby 2.0/2.1 on travis.

Allow failures on 2.1 vmdb test suite.

Enable fast_finish so a PR is green without the required 2.1 vmdb suite:
"Now, a build will finish as soon as a job has failed, or when the only jobs left allow failures."
http://docs.travis-ci.com/user/build-configuration/#Fast-finishing
http://blog.travis-ci.com/2013-11-27-fast-finishing-builds/
Merge pull request #185 from jrafanie/ruby_2_x_support

Upgrade to Ruby 2.0