FIX #556 refactor word-wrap

Small refactor of the `word-wrap` mixin. Moved `overflow-wrap` outside of the if statement since this actually is the new preferred CSS3 name, if not supported (not Chrome or Opera) `word-wrap` would be the fallback.

`word-break` gets the same value as `overflow-wrap` for `normal` and `inherit` which allows it to be reset.