feature(client): Add input field validation errors to the event stream.

fixes #1297
chore(l10n): update string templates for train 16
Merge pull request #1307 from mozilla/update-strings-train-16

chore(l10n): update string templates for train 16
fix(client): Firefox for Android Sync marketing material is only available to desktop sync users.

fixes #1041
Refactor the marketing snippet logic.

* Extract the marketing logic from `ready.js` to `marketing-snippet.js`
* English speakers always see some form of marketing.
* If an english speaking sync on desktop user is not selected to see the survey, they will see the `Get Firefox for Android` marketing.
* Non-english speaking sync on desktop users always see the `Get Firefox for Android` marketing.
feat(server): Add `x-content-type-options: nosniff` headers to prevent browser content type sniffing.

fixes #1165
feature(test): Add a `/clear` route that clears browser state.

* Used in the selenium tests instead of running `unsafeEval` or `eval`

fixes #1285
feat(client): Add email prefil on the `/signup` page if an email is passed as a URL search parameter

fixes #1285
feat(client): Add email prefill on the `/signin` page if the email address is passed as a search parameter.
Merge pull request #1301 from mozilla/issue-1297-local-errors

feature(client): Add input field validation errors to the event stream.
Merge pull request #1309 from mozilla/issue-1165-nosniff

feat(server): Add `x-content-type-options: nosniff` headers to prevent browser content type sniffing.
Cleanup - remove last `eval` from functional tests, remove unnecessary jshint directives.
Extract duplicate logic to fetch a search parameter into `BaseView.prototype.searchParam`
fix(l10n): upgrade jsxgettext to handle nested handlebar clocks

Fixes #1306.
Merge pull request #1312 from mozilla/issue-1258-email-prefill-signup

add email prefill to /signup and /signin pages
Merge pull request #1322 from mozilla/issue-1306-jsxgettext-bug

fix(l10n): upgrade jsxgettext to handle nested handlebar clocks
Merge pull request #1299 from mozilla/issue-1041-hide-sync-for-most

fix(client): Firefox for Android Sync marketing material is only available to desktop sync users.
fix(oauth): ensure oauth forms are enabled if valid on afterRender
Merge pull request #1310 from mozilla/issue-1285-selenium-without-eval

feature(test): Add a `/clear` route that clears browser state.
Merge pull request #1325 from mozilla/issue-1320-oauth-pause

fix(oauth): ensure oauth forms are enabled if valid on afterRender