Update README.rdoc

Add travis-ci and code climate badges.
Update README.rdoc

Add gemnasium dependency status.
GFM Readme.
Consistent quotes.
Fix rake dependency.
Provide core extensions with Active Support.
Merge pull request #111 from heroku/active-support

Active Support
Bump version.
Adds ruby 2.0.0 to CI
Fixes path to shared_behaviors
Merge pull request #118 from mscottford/topic/ruby-2-0

Fixes specs on ruby 2.0.0
Merge branch 'master' of https://github.com/heroku/databasedotcom