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
fix(test): Fix the reset password related tests that were broken by the new form prefill features in #1048. Ensure sufficient test coverage in the sign_in mocha tests.
fix(build): Fix IE 404s when requesting .eot fonts in prod.

* Update the version of grunt-usemin which fixes the problem.

fixes #1033
Merge pull request #1040 from mozilla/issue-762-confirm-reset-from-signin

feature(client): Send password reset email from /signin if user has filled out a valid, known email.
Merge pull request #1101 from mozilla/issue-1033-eot-fonts

fix(build): Fix IE 404s when requesting .eot fonts in prod.
refactor(test): Use a single function to fill out the sign up form. Fixes #1100.
chore(l10n): extract strings and update templates for train 13
Merge pull request #1103 from mozilla/extracted-strings-train-13

chore(l10n): extract strings and update templates for train 13
Merge pull request #1102 from vladikoff/issue-1100-test-selects

refactor(test): Use a single function to fill out the sign up form.
fix(client): update js-client to 0.1.19 for request timeouts
Merge pull request #1104 from mozilla/update-js-client-0-1-19

fix(client): update js-client to 0.1.19 for request timeouts
chore(deps): update dependencies

Fixes #1060.
Merge pull request #1106 from mozilla/issue-1060-update-modules

chore(deps): update dependencies
refactor(client): Replace modernizr with html5shiv and a short test for js and touch screen.

fixes #1021