[failing] Add specs for dirty context tag lists

Related #321.

Split tests for single-assertions
Call context-specific includes for each taggable_on call

Don't include Utils multiple times
Modernize and cleanup gem plumbing

Moved version into the gem namespace
Modernized and updated the gemspec
Merge pull request #339 from shekibobo/dirty-context-tags

Fix dirty checking for subsequent calls to taggable_on. Fixes #321.
now tracking version 2.5.0
Update readme with up to date release planning

Also mentions compatibilities I want to see maintained.
These might still change though, depending on feedback from
the community.
Only return tags from the owner in a 'tagged with any' query
Merge pull request #337 from jsteiner/js-fix-tagged-with-ownership-query

Only return tags from the owner in a 'tagged with any' query
remove unused uninstall file
Readme improvements

Remove changelog. Useless and confusing when it's not maintained.
Renamed MIT-LICENSE.md to LICENSE.md. Contents unchanged.
Remove outdated copyright notice.
Make the compatability more explicit.

<3
make UPGRADING notice display post gem install
only use attr_accessible if it's supported

Rails 4 doesn't define the ActiveModel::MassAssignmentSecurity constant,
but there is a gem that allows it to be used. The models will now only
try to use the functionality if the constant is defined
Use of these methods is preferred for Rails 4

The Relation#all method is deprecated as of Rails 4, we should use these
to acheive the desired behavior.

yep.
Merge remote-tracking branch 'origin/master'
Merge pull request #348 from cwoodcox/rails-4/deprecation

Use of these methods is preferred for Rails 4
Merge remote-tracking branch 'origin/master'
only bump patch version
Merge pull request #346 from cwoodcox/rails-4/attr_accessible

only use attr_accessible if it's supported
now compatible with Rails 4

<3 cwoodcox
Mention Rails 4 compatibility in the readme.