refactor(build): Remove fxa-auth-server as a devDependency.

* fxa-auth-server is only needed for travis and slows down local `npm install`s. Install it on travis via the .travis.yml file.

fixes #971
fix(server): Ensure the browsehappy text is translated

fixes #821
chore(client): Shorten rate limited error message.

* Change to `Attempt limit exceeded.`

fixes #892
Merge pull request #974 from mozilla/issue-892-rate-limit-text

chore(client): Shorten rate limited error message.
Merge pull request #973 from mozilla/issue-821-browser-happy

fix(server): Ensure the browsehappy text is translated
chore(build): remove extra npm install
Merge pull request #972 from mozilla/issue-971-auth-server-dep

refactor(build): Remove fxa-auth-server as a devDependency.
tests(functional): more functional test hardening
Merge pull request #978 from mozilla/more-functional-test-hardening

tests(functional): more functional test hardening
feature(client): Add a spinner!

Displayed on:
* App startup
* 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