Re-generate test files with wp-cli

Add composer.json, phpunit development dependency.
Fix failing roles / capabilities test cases

Section Editor role was not being defined due to a change in the WP tests suite
Move phpunit / selenium tests into subdirectories

Add note that Selenium tests are based off of private wp-unit-tests fork.
Add Grunt for Javascript compilation

Switch from .dev.js -> .min.js for minified files
Remove unused copy of jstree
Add CONTRIBUTING.md
Correct bad WP_VERSION in .travis.yml
Fix warnings leading to test failures in PHP 5.4

Missing static keyword, assigned by reference warnings.
Fix more pass-by-reference errors
Merge branch 'build' into develop
Style tweaks to permissions editor

Fixes a few issues introduced by recent WP admin CSS changes.
Tweaks for jQuery Autocomplete styles
Fix autocomplete CSS regression

jQuery UI Autocomplete 1.11.0 removed <a> tags with .ui-meni-item <li>.
Merge branch 'feature/ui-41' into develop
Version bump to 0.9.3
Merge branch 'release/0.9.3'