Use the latest version of 2.0.0 for development
Remove Gemfile.lock

It should not be included in repos for rubygems development:

http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/
Add some common RSpec options

* Use color
* Use documentation for individual specs
* Use progress format for rake
Merge pull request #40 from jgdavey/common_dev

Some common development niceties and best practices