fix(server): Ensure fonts have cacheable URLs.

* Serve fonts statically until connect-fonts has its business in order.

fixes #384
chore(client): Change `too many retries` to `Unexpected error`.

* Used if browser does not respond to a message sent to it.

fixes #725
Merge pull request #896 from mozilla/issue-725-too-many-retries

chore(client): Change `too many retries` to `Unexpected error`.
feat(client): updating js client to 0.1.18
Merge pull request #899 from vladikoff/js0.1.18

feat(client): updating js client to 0.1.18
Merge pull request #890 from mozilla/issue-788-async-render

refactor(client): Asynchronous rendering!
Merge pull request #895 from mozilla/issue-384-cache-fonts

fix(server): Ensure fonts have cacheable URLs.
feature(client): Check email verification tokens before rendering.

* URL parameter validation for `/complete_reset_password` and `/verify_email`
* Add validate.js for a central place to do validation.
* Update form to validate email addresses using validate.js
* Validate emails, tokens, and codes on the client.
* Handle errors sent by the server that says uid or code is bad.
* Handle expired tokens by giving the user an opportunity to resend the email.
* Add unit and functional tests for corner cases.

fixes #788