Move development dependencies into Gemfile
Form-Encoded Body Parameter was finally access_token

http://tools.ietf.org/html/rfc6750#section-2.2
Add bundler development dependency
require 'oauth2/version'

Because require hashes based on the string, not the expanded path of the
file, it's important that we require the version file the same way that
it will be required elsewhere to avoid constant warnings.
Use of custom objects is not necessary here
Merge pull request #128 from atd/master

Form-Encoded Body Parameter was finally set to "access_token" in RFC6750
Don't implicitly require simplecov
Specify minimum rspec version
Add official support for Ruby 2.0.0 [ci skip]
Reword [ci skip]
Use relative links [ci skip]
Add cryptographic signature
Remove rdoc from development group
Bump version to 0.9.0
Add Gem Version badge [ci skip]
Add Code Climate badge [ci skip]
Update copyright year [ci skip]
Add gem signing instructions [ci skip]
The source :rubygems is deprecated because HTTP requests are insecure.
Convert expires_at to integer