Fix compatibility with Rails 4/Arel 4.0.1.

The method signature of the Arel stuff changed in the 4.0.1 release:
https://github.com/rails/arel/commit/68a95542e1a7a79d9777223fbffd2b982fed0268

This adds some basic tests surrounding this Arel functionality using a
FakeRecord class taken from how Arel performs its own tests.
Use Appraisal to make local testing with multiple Rails versions easier
See about cleaning up rubinius support on Travis.
Merge pull request #12 from GUI/arel401

Fix compatibility with Rails 4/Arel 4.0.1
Merge pull request #13 from GUI/appraisal

Use Appraisal to make local testing with multiple Rails versions easier
Version 0.6.0
Simplify Rakefile

* Use standard bundler gem tasks
* Use standard rake test tasks
Require ruby 2.0.0, activerecord 4.1

* arel dependency is unnecessary
Update Gemfile, drop jruby support

* Use https rubygems url
* Update appraisal version
* Remove activerecord dependency - it is defined in the gemspec
Update appraisals. Test against ActiveRecord 4.1+
Use mintiest

* Drop support for old Arel versions
Update gemspec, remove ".nonrelease" from version

* Add minitest development dependency
Simplify versioning, prepare for 1.0.0

* Remove versionomy
* Remove Version file

Conflicts:
	Version
Remove semicolons
Remove old AR cache clearing in AdapterTestHelper
Remove old Arel hacks
Remove TaskHacker
Remove unnecessary require
Less code
Cleanup requires, whitespace

* Remove unnecessary empty module declarations for Arel and ActiveRecord