Adding behat tags to valid and recommended tags

Adding them at the beginning following ASCII
chars order.
New rule to validate tags against paths.

Some of the tags are only valid under certain
directories, this new rule is built on top of
existing valid and recommended and verifies
that the tags are only used into valid paths
(usually behat/phpunit paths).
Merge pull request #17 from stronk7/behat_valid_tags

Behat valid tags