Add an option to honor emailVerified

/to @ritch or @bajtos 
The PR should supersedes https://github.com/strongloop/loopback/pull/215
Well, are you expecting that the code rendering the response body depends on the value of `emailVerificationRequired`? I would certainly not expect that, in which case there is not much value in testing that.

If you feel the asserts are worth the extra maintenance cost, then leave the in and merge the patch as it is now.