Attempting to fix #144.
Required and extended paper_trail.rb to include the cleaner module I created.
Added a grouping_by_date method to version.rb. This method, used in conjuctioned with group_by allows a version to be split into separate days.
Cleaner module with methods for grouping, analyzing, sorting and then sanitizing(removing) extra versions.
Added tests for the new methods created for cleaning paper trail versions.
Namespacing version class under the PaperTrail module. Fix #165
Merge branch 'patch_for_issue_144' into version3
Dropping unnecessary secondary sort on versions association, fix #235
Skip any changed attributes marked to skip in the PaperTrail options - helps to resolve #224
Restrict changed attributes to attributes that have a corresponding database column
Update CHANGELOG and README [ci skip]
Update README.md [ci skip]

Clarify that versions call is on an instance not the class
Updated the cleaner module to give the clean_paper_trail_versions method the option of passing in a value. Also created a keep versions method that keeps the specified number of versions.
Added an additional test to test the passing in of a variable number of versions to keep.
Merge remote-tracking branch 'SeanMarcia/master' into cleaner

Conflicts:
	lib/paper_trail/version.rb
Refactoring the Cleaner module to have condensed and more readable code, and better tests
Changing the :clean_versions! method on the Cleaner module so that it accepts an options hash as an argument, and additional configurable options.
Merge branch 'rails4'

Conflicts:
	README.md
	lib/paper_trail/has_paper_trail.rb
	lib/paper_trail/version.rb
	test/dummy/config/initializers/paper_trail.rb
	test/unit/model_test.rb
	test/unit/version_test.rb
Adjusting Travis CI config to cover ActiveRecord 3 and 4 and allow failures when appropriate, tweaked 3.0.gemfile so it can handle ruby18 and jruby
Adjust CHANGELOG to mention Cleaner module; bump version to 3.0.0beta [ci skip]