Install appraisal to test against different Rails versions
Added appraisal scenarios for Rails 3.2 and 4.0
Added scenarios to Travis
Specs (except those for Railtie) pass against Rails 3.0
Most specs pass in Rails 3.2 and 4.0

- Rails 3.0 deprecated request_uri in favor of fullpath
- Rails 3.1 changed default format in Active Resource
  to JSON
Header specs pass in Rails 4

Need to pass the date differently, see
https://github.com/rails/rails/issues/11110#issuecomment-20044511
Test against most recent Rails version first
All specs pass on Rails 4 and 3.2, but not 3
Run specs against 3.1, not 3.0 – GREEN!
Tell Travis to not run tests against top-level Gemfile
Do not list rspec as development dependency

Otherwise, Travis will return an error with:

> Your Gemfile lists the gem rspec (~> 2.4.0) more than once.
> You should probably keep only one of them.
> While it's not a problem now, it could cause errors if you change the version of just one of them later.
> You are trying to install in deployment mode after changing
> your Gemfile. Run `bundle install` elsewhere and add the
> updated Gemfile.lock to version control.
Revert "Do not list rspec as development dependency"

This reverts commit eb86375cad4cadd822154c399f9e6def3497bd5b.
Drop rspec from all appraisal scenarios

(we don't need to test against different versions of RSpec)
Merge branch 'master' into pr35

Conflicts:
	Gemfile.lock
Support raise 2.3 and 3.0
Updated gemfile locks
Downgrade mime-types gem
Merge pull request #40 from kjg/appraisal

Test multiple rails via Appraisal