LowercaseConstantsFixer - rewrite to handle new test cases

LowercaseConstantsFixer - rewrite to handle new test cases.
Resolves #793.

May not work on php 5.3 yet
> `if (!defined('T_TRAIT') && 'trait' === strtolower($token->getContent())) {`

And what you done there has been done in in very hacky way.
Want to add a support for `T_TRAIT` in PHP 5.3? Do it a proper way and register this const in Transformers. There are no good reason to made it by hack, and only in one Fixer!