Fixed regexp for directives pattern

Same comment as previous PR:

Previous regexp matched javascript strings, like this:
```
) !== false) && that._onSend(e, this);
```

 and resulting file sometimes appears to be broken.

Example project: https://www.dropbox.com/s/350qtn07phy5u26/sprockets_bug.zip?dl=0


This time fixed relative paths and updated tests.