feature(client): debounce resend button clicks.

* Send emails on the first and forth attempt. Shake the success message otherwise.
* After the forth attempt, hide the resend button for 5 minutes.
* Change the name of `.error-shake` to `.shake`.
* Update `.shake` to cause 8px of movement, not 100px.

issue #885
feature(client): Prevent users from seeing confirmation pages if they have not initiated the process.

* For /confirm, redirect to /signup
* For /confirm_reset_password, redirect to /reset_password

fixes #847
feature(client): Add a button spinner!

Displayed on:
* View render
* Form submit

* Add a new static function to Base - Base.withProgress. This shows a progress
 indicator if the action takes a long time.

fixes #371
Pass {{link}} url into outlook-specific markup in email templates.
Merge pull request #1028 from mozilla/rfk/fix-link-rendering-in-outlook

fix(email): Pass {{link}} url into outlook-specific markup in email templates.
tests(functional): fix promise return, clean up.
Merge pull request #1035 from vladikoff/test-promise-fix

tests(functional): fix promise return, clean up.
Merge pull request #923 from mozilla/issue-371-user-feedback-spinner

feature(client): Add a button spinner, animate success/error messages.
Merge pull request #1005 from mozilla/issue-885-debounce-resend-email

feature(client): debounce resend button clicks.
Merge pull request #1012 from mozilla/issue-847-no-user-no-confirm

feature(client): Prevent users from seeing confirmation pages if they have not initiated the process.
chore(l10n): update l10n templates for train 12