Remove white space
Fix respond_to? for ruby 2.0
Add ruby 2.0.0
Merge pull request #130 from mittel/respond_to_ruby2.0

Fix respond_to method for ruby2.0
Add ruby 2.0 travis test coverage.
Update appraisal gem and source for rubygems.

Use current https source for rubygems, avoid annoying warnings.
Update appraisals's generated gemfiles.
Turn on mongodb for travis.
Allow failure on ruby2.0, not supported yet.