Enhancements to update_enumerations_model.

The enum models are no longer frozen when inside an
update_enumerations_model block.
Added 'contains?' method to enum classes.

This implements a mechanism to readily determine if an item looked up by
a particular String, Symbol, or id exists in the enumeration.
See PowerEnum::Enumerated::EnumClassMethods#contains?
Add enumerations as associations

This allows power_enum to play nicely with tools like ActiveAdmin which
look at associations and have no idea about enumerations. Since
enumerations act like belongs_to associations, this works for such
tools.
Updating version to 0.11.0 for release.
Fixing minor issues with enum reflection.
1.0 Release, yay.

Mostly cosmetic changes.
* Temporarily using my fork of genspec while my pull request is reviewed.
* Dropped support for Rails 3.0, as it's no longer officially supported.
* Added documentation.
Adding code coverage metrics.

Using SimpleCov to measure code coverage.
Wrote several new specs to deal with gaps.
Improved error message of act_as_enumerated matcher.

Matcher now has an improved error message that make a bit more sense.
Added test coverage for RSpec matchers.
Added test coverage for virtual enumerations.
Test coverage now adequate (99.55%).
Working on getting Travis running.

DB test setup is now scripted.
Updated README
added .travis.yml
Working on Travis:CI integration.
Disabling JRuby environment for Travis:CI.

I'd rather not deal with SQLite and juggling different DB adapters right now.
CodeClimate integration

Added badge to readme and updated TODO list.
Internal refactorings.

Internal refactorings to make the acts_as_enumerated and has_enumerated
macros somewhat manageable.
Updating generator specs.

Implemented more extensive specs for enum generator.
Updating version to 1.1.0.

PowerEnum is now digitally signed.
Update README.markdown

Updating CodeClimate badge.
Internal housekeeping. Took the opportunity to refactor some eyesores.

Moved the Module patching logic into VirtualEnumerations.
Cleaned up some code in acts_as_enumerated.
Refactored how Module#const_missing is patched by virtual enumerations.

Module#const_missing is now patched when we run VirtualEnumeraions.define for
the first time instead of the PowerEnum engine initializer.  Patching Module
in the initializer seemed heavy handed since virtual enumerations are an
optional feature.
Improved test coverage of the enum generator code.
Enumerated attributes can now be used in a join.

Added logic to EnumerationReflection so models with enuerated attributes can
join on those attributes.  This is rarely needed unless you're using AREL to
generate some custom SQL.
Adding the method necessary for ransack_ui.