Add icons to links in _links.tpl

Uses g.etfv.co and specifies a default icon; now uses HTTPS exclusively.
Make link icons https safe, add tests.
Disable photos in stylestats

Commenting it out, not removing.
We'll want to turn it back on once we update the handling of photos
in the crawlers.
Show special case text for allaboutme percentage being the same.
Update favorited_links to use $post->links and exclude twitter photos

Also updated with new tests
Only show frequency insight when there is text.

In practice, this is when there is a baseline to compare
or not posts.
Add commas to weekly graph text numbers when needed.
First pass on improving the styling of the weekly interactions bar chart
Signup touts, some of which have text specific to certain insights.
ThanksCount insight and CriteriaMatchInsightPluginParent

CriteriaMatchInsightPluginParent is a parent class for insights which look at some posts
    and track the change in how many posts match something over time.
InsightBaselineDAO::getMostRecentInsightBaseline() is added to support this.
ThanksCount is an implementation that looks at thankful posts.

ThanksCount copy tweaks

Capitalize network names in copy.
Change 1 time to once.
Split headline into two options.

Update CriteriaMatchInsightPluginParent and ThanksCount

Add docblock about parent class.
Add more variety to ThanksCount output.
Use getOccurrencesAdverb.

Thanks count - register insight, improve copy

Update thankscount postmatcher to exclude self-replies and updated headline

Only show %username %posted X thanks when there is a thankee.
Update amplifier insight

Add alternate text and multiplier text vs absolute text.
Add tests.

Added additional amplifier text version.  BOOSTED.
Insight sign up touts should link to somewhere meaningful
Copyedits to insight-specific touts
Hotfix for broken link favicons
Hotfix for broken link images, part 2
Fixed the janky avatar-less users, cleaned up the header image styling.

And now we have some description text in the emails, too.

Tests for descriptions.
First few test fixes for new sessions templates.