Remove unused variables
Introduce pattern capture filter for user field.

This way we can search both for the username and the full user format.

Fix #1456
Get rid of the exact_match configuration parameter

As now we only use it with a false parameter every time,
it is no longer serving any purpose
Remove the d3 dependency
WIP update heatmap plugin to work without d3
Remove _colorize method from heatmap
Tweak logging setup

Change the logging setup to use the same format as Gunicorn defaults.
Strip the redundant default args to the console handler. Remove the
extra loggers whose defaults are fine. Remove the access log config.
Set the root logger in development.ini to INFO.

I had a fundamental misunderstanding of Python loggers. I thought that
for a logger to handle a message its effective level was determined by
traversing all the way to the root and clamping the log level to the
highest configured logger. It turns out that it's the first ancestor
to have a level set that determines the effective level. Therefore,
it's sufficient to set 'h' to DEBUG but leave the root at INFO in
order to get debug message from the application and info messages
from other packages.

The gunicorn.access logger is unnecessary to configure. It isn't
enabled without a switch in the server config, or a --access-logfile,
so we'll leave it out.

I also removed places where I wrote WARN instead of WARNING (all of
these were redundant since NOTSET is the default and WARNING is the
default for the root) or had the propagate setting redundantly set to
True (also the default).

Close #1512
Use more compatible :after instead of ::after
Create heatmap tags from index

This makes the style and attribute iterators work correctly
Re-use tabs in the heatmap plugin

This improves performance while scrolling as we're no longer destroying
and recreating every tab on each call to update.
De-bounce all calls for heatmap to update

Previously it would update on every scroll or resize event fired on
either the document or body.
Remove the SVG element from the heatmap

Replace the background with a grey bar using a div.
Merge pull request #1511 from hypothesis/remove-d3

Remove d3 dependency
Rename username ES filter to user
Merge pull request #1481 from hypothesis/1456-fix-user-search-2

Search for usernames
Add markdown insertLink and insertIMG functions
Create lightweight markdown editor from scratch

Code cleanup.

First pass at implementing @aron's mockups.

Fix bugs, breakout markdown into its own directive

Forgot to add markdown.coffee
Add checks to see if markup has already been inserted
Fix bugs by getting rid of a bad idea. Tighten up styles.
Add ngDoc documentation to markdown.coffee