Let's lint the app/test/ files
fix(tests): Fix the jshint errors and warnings in all of the tests.

* Remove all of the remaining `global: *` declarations
* Remove or comment out all veriables that are "defined but never used"
* Use dot notation where it is "better" (very subjective)
* Make unreachable code reachable.
A couple more tweaks from Shanes meta-PR
fix(tests): Add a missing semicolon.
Merge pull request #1072 from mozilla/molint-moproblems

Molint moproblems

Travis is green. I'm merging. Thanks for this effort @pdehaan!
feature(client): Smooth the `forgot password` experience from `/signin`

* Send password reset email from /signin if user has filled out a valid, known email.
* Show user the `Unknown user. Sign up.` error message if valid, unknown email.
* Send user to the `/reset_password` page and pre-fill any partial emails otw.

fixes #762