Fix email address verification for CLA form

<a href="https://github.com/prksingh"><img src="https://avatars.githubusercontent.com/u/1701706?v=4" align="left" width="96" height="96" hspace="10"></img></a> **Issue by [prksingh](https://github.com/prksingh)**
_Friday Jun 19, 2015 at 10:31 GMT_
_Originally opened as https://github.com/adobe/brackets/issues/11290_

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Add support for generic domain names in the CLA check form.

