Fix CS strings with {{helper key="value"}}

Hey @tchak, I wanted to run this by you before committing it to master. Apparently newer versions of handlebars cannot contain literal '\"' in them. So if you write coffeescript like this:

```coffeescript
Ember.View.extend
  template: Ember.Handlebars.compile """
    {{action target="view"}}
  """
```

You'll get a lovely error. I updated the regex sanitization to remove all literal '\"' from the templates. If you're ok with this please merge it and we can release version 0.4.2.