Added a PHP_CodeSniffer review.

See http://pear.php.net/package/PHP_CodeSniffer for more information.

Uses the csv report format to easily parse the results. Default
standard is PEAR, but this can easily be changed by calling `setStandard`
on the review.

Use of `setStandard` can be seen in hooks/static-review-pre-commit.php,
where it uses the PSR2 standard. Internally this just adds `--standard=?`
to the `phpcs` command line call.
Merge pull request #21 from sjparkinson/feature/php-code-sniffer-review

Adds a PHP_CodeSniffer review