Add analytics to the subtitle editor

Moved the analytics code block into a separate template and included
that from subtitle-editor.html.

Simplified the cases for when we don't use analytics because we're
running from dev or something.  Before we sometimes would set up the
code, but not include the script.  Or we might include the github CSS
and highlight JS.  Both of these things seemed pretty weird, now
we either show the analytics, or show a comment instead.
Added analytics to embedder
Added new analytics code

This is the new recommended code.

Removed Loading the script at
http://cdn.optimizely.com/js/12019399.js
I have no clue what that's supposed to be.  I'm guessing it's just a
minified version of the old analytics.
Embedder has the option to disable analytics tag, to be used on amara.org to avoid counting pages twice. Also removed duplicated tag in analytics template, and deleted unused templates
Merge pull request #1626 from pculture/analytics

Analytics