Fix ruby 1.8.7 errors

* Errors noted when running TravisCI on other rubies (https://travis-ci.org/yammer/yam)
* Add json as required gem for ruby 1.8.7
* Add before_install section to run lastest rubies on Travis
* Bumped version number to 0.0.6

Minor:
* Add `.bin/` to .gitignore to exclude binstubs
* Sort required gems/libraries
* Update authorship information
* Make Travis badge a link

Trello: https://trello.com/c/20xiPexq