Remove RSpec #should syntax to support Test::Unit

There was no need for us to call `#should` in those matchers, as we only
need to return true/false in `#matches?` method. By removing those
`should`, those two matchers are now working fine with Test::Unit
and minitest.
add license information to gemspec

this way it can be used with rubygems.org API
Merge pull request #231 from jordimassaguerpla/master

add license information to the gemspec
Update copyright year to 2013
Uses secure RubyGems URL
Merge pull request #242 from vfrride/patch-1

Uses secure RubyGems URL
Allow the suite to run sequentially via Appraisal, or one at a time with BUNDLE_GEMFILE set
Merge pull request #247 from thoughtbot/mj-rakefile-appraisal

Allow the suite to run sequentially via Appraisal
clean up documentation in validate_uniqueness_of
ValidateFormatOfMatcher#description: "have a valid format for #{@attribute}"
Rename failure_message and negative_failure_message

* fixes #108 : RSpec 2.10 compatibility
* remove unnecessary attr_readr
Modified default attribute error message generation

Generation of the default attribute error message is now delegated to
ActiveModel::Errors where possible, avoiding inconsistencies where
default locale entries have been overridden from the ActiveModel
defaults and other divergent behavior.
Refactored delegation of error message generation

Moved delegation to ActiveModel::Errors#generate_message to
default_error_message and implemented a spec for it.
Fixed typo in spec for error message generation
Refactored error-generation spec to use inline fixture
Ensure that `should` is on the same line as the expectation
Remove duplicated method.
Remove unneeded test that should not have passed.
Deprecate matchers for 2.0 release.

* Deprecates matchers from issue #252:
* assign_to
* respond_with_content_type
* query_the_database
* validate_format_of
* have_sent_email
* strong_parameters_matcher
* delegate_method
Bump to version 1.5.0