Add a with_message option to comparison matcher.
Use 1.9 style syntax
Create a shared example for Numercial Submatchers.

* Verify that all submatchers respond to the necessary interface
* See: #357 for a reason why this is necessary
Bump to version 2.4.0
Don't extend non-existing modules

Fixes an issue where a Rails project skips the test unit railtie
completely, eg:

# require "rails/test_unit/railtie"
Added "should accept_nested_attributes_for" example on README
Update NEWS for #363
Add `validates_presence_of` example with `on` option
Correct behavior of with_message with ensures_length_of and is_equal_to matchers
RouteMatcher#to accepts a string as first param

Some refactor
Upgrade to appraisal 1.0.0.beta1, clean up Rakefile
Merge branch 'master' into ew-fix-rake-to-install-appraisals