Replace counter with static headline and other string updates

* [Bug 1002672](https://bugzilla.mozilla.org/show_bug.cgi?id=1002672) - **Replace Counter**
  * Updated the JS to check for the share_total span and short-circuit the counter logic if the element doesn't exist.
  * Updated the CSS to show the headline immediately, rather than waiting for the count to fade-in.
* [Bug 1002677](https://bugzilla.mozilla.org/show_bug.cgi?id=1002677) - **Add Link To Get Involved Page**
* [Bug 1002673](https://bugzilla.mozilla.org/show_bug.cgi?id=1002673) - **Add Link To Faq**
   * Just a placeholder, hidden by CSS, to get the string in for l10n