Add new rubies to travis-ci builds

Add ruby 2.0 and 2.1 and rubinius 2.2.
Merge branch 'feature/newer-rubies'
Add coveralls
Support coveralls and local report when not on travis-ci
Add CodeClimate badge to README
Add gemnasium badge to README
Add gem version badge to README
Merge branch 'master' into feature/coveralls

Conflicts:
	README.md
Merge pull request #54 from rapid7/feature/coveralls

Upload coverage reports to coveralls.io
Update Coveralls badge URL
Merge branch 'master' into remove-report-related