Created the YUI Compressor Check class to flag JS issues.

As requested on https://github.com/Automattic/vip-scanner/issues/69 a new Check class was created to test all the JavaScript code using the YUI Compressor.
The latest binary is included, and also PHPUnit tests are included.
Merge remote-tracking branch 'upstream/master' into yui-compressor

Conflicts:
	vip-scanner/config-vip-scanner.php
Renamed the YUICompressorCheck Class to JavaScriptLintCheck
JavaScript Lint tests now have the files bundled.

Instead of creating temporary files, the PHPUnit will read the correct files, bundled in the tests directory.
Added sanitization to the shell command arguments.

To avoid issues with the YUI file name and with the javascript file path, sanitization has been added to the command arguments.
The argument sanitization is now made using a private class method.

This method first remove all the possible extra arguments and then, if wanted, applies the escapeshellarg.
Merge pull request #143 from vaurdan/yui-compressor

Created the YUI Compressor Check class to flag JS issues.