Fix uninstall to properly clean up after us

We generate two non-Ruby files in the Gem bin dir--shoes (during gem
install) and shoes-backend (during the first run or picking a shoes
backend).

The shoes binary wasn't getting uninstalled because we weren't putting
the lib/rubygems_plugin.rb file into the gem itself.

shoes-backend was a recently added file that got missed on adding to
cleanup when I created it.
Test all .rb files show up in some manifest

We've had at least two problems resulting from files in the repo that
didn't get added into a manifest and hence were missing from the gem.

Time to start testing for it!
Don't need class var on module, just use instance
Small revisions thanks to PragTob.
Merge pull request #936 from shoes/not_included_files

Fix to uninstall shoes executable correctly

* Changelog: bugfix
* also includes an amazing tests to see if we have all .rb files in our manifest
Extract separate shoes-highlighter gem

Update the help system to use the new location.
Necessary gemspec to build shoe-highlighter
Bundler support required by new file structure

Previously our separate 'gems' have worked fine from source simply
because they're all in the lib folder together. Changing that to be
split into separate gem directories actually breaks things unless we get
Bundler into the mix to get our proper load paths set.
LICENSE and README tweaks for new gem
In development use by path, not gemspec

Travis didn't seem happy with it by gemspec and tried to install from Rubygems.
Fix for using shoes-highlighter by path

Was the relative pathing in gemspec that was problematic
added a basic tetris game to the samples
Add modal windowing

Adds style to Shoes.app calls for making things modal.

Also supports a #wait_until_closed so we can hold until we get an answer
for model dialogs.
Shoes-based implementation of ask dialog
Don't need that old SWT ask anymore
constantize some magic numbers, and s/dir/direction
Revising version number on shoes-highlighter

Will eventually be independent from main Shoes, so treat it as such.
Merge pull request #938 from jakesgordon/tetris

Tetris sample game

Changelog: improvement
More common way to reference local gem by path
Merge pull request #939 from shoes/shoes_ask

Better input sizing on ask dialog

* Changelog: improvement
* Replaces the SWT implementation with a shoes implementation, better reusability but might give us headaches down the road through multi app, let's see :)