fix(l10n): use a less spammy email headline

Fixes #1849.
feat(client): Allow TLD only domain names in email addresses

The email `user@com` is a valid email according to the IETF RFC5321. Marketplace allows them. We should too.

http://tools.ietf.org/html/rfc5321#section-4.5.3.1.1

fixes #1871
fix(test): Remove the inter-test dependencies in the reset-password tests.

fixes #1831
maybe fixes #1834
fixes #1835
Merge pull request #1909 from mozilla/issue-1871-tld-email

feat(client): Allow TLD only domain names in email addresses
Merge pull request #1904 from mozilla/issue-1849-change-email-headline

fix(l10n): use a less spammy email headline
refactor(cropper): pass crop image data around using ephemeral messages

Fixes #1912.
Add `initiateResetPassword` to programatically initiate a reset password.
Merge pull request #1911 from mozilla/issue-1831-reset-password-tangle

fix(test): Remove the inter-test dependencies in the reset-password tests.

DRY updates made, @zaach gives the r+, merging.

Thanks for reviewing @zaach!
Merge pull request #1915 from mozilla/issue-1912-cropper-ephemeral

refactor(cropper): pass crop image data around using ephemeral messages

This PR looks great, and Session is shrinking! Thanks @zaach.

r=shane-tomlinson
fix(test): Fix the 'Unexpected error' flash in the sign_in tests.

This is a dirty hack to avoid a timing problem that causes
an 'Unexpected Error' to be displayed in the 'sign in verified
with password that incorrectly has leading whitespace' test.
The XHR request for the signin request can still be open when the test
completes. If the test finishes immediately, the page redirect closes
the XHR request and flashes an 'Unexpected Error' while waiting
for the next page load.

Also moved a couple of reset password related tests to reset_password.js

fixes #1875