Add SITE_URL for Persona.
[bug 897663] Fix links to AAQ on registration page
[bug 889426] Large images displayed in AoA
[bug 898045] Add syntax autocomplete to highlighting editor
[bug 697840] Better presentation of images in KB articles
[bug 899507] Add image upload modal to media page
[bug 896335] Update favicons to new logo
[bug 898045] Followup: Replace tabs with \t
[bug 898045] Followup: Add ext-language_tools.js to wiki.editor bundle
[bug 898045] Followup: Adding semicolon to silence evaluator
[Bug 881210] Make product header flow right on RTL
Move html5lib from packages to src.
Update docs to reflect https URLs for repos.
[bug 898769] Go back to PLACEHOLDER + string replacement for youtube iframes.
[Bug 898001] Create table of content for Kitsune admin documentation
Minor formatting fixes in docs
New favicon on mobile
[bug 895393] Remove deprecated selector interpolation
Fix tests.. s/revision id/document id/

These were passing by pure luck.
[bug 896484] Track the number of active contributors per locale/product.

* Added a new utility function to get # of active contributors
  per locale+product
* Added a new monthly cron job that calls it for each locale+product
  and saves the results to the WikiMetric table
* Created a new migration that backfills the data for this year
* Tests for the utility and cron job