Fix a few JS warnings that pop into the console
call correct highlightNodes function, fixes #550

colourHighlightNodes is never added to the global object, so calling it that
way resulted in a "function undefined" error. I believe this was due to an
earlier PR comment where I recommended we not add it to global because it is
only ever used inside graph.js. This is probably a leftover line that wasn't
changed for that comment.
Merge pull request #559 from mozilla/fix/empty-graph-after-blocking

call correct highlightNodes function, fixes #550
Fix the least controversial jshint warnings

To install jshint, simply `npm install jshint` from the root
directory of the project. Then run like it like this:

    node_modules/.bin/jshint data/*.js
Remove unnecessary execute bits on files

These files should not be executable
Point Feedback link to an email alias instead of Google Docs (fix #501)
Merge pull request #548 from fmarier/issue501

Remove link to Feedback Google Docs (fix #501)
Add a note about running jshint in the CONTRIBUTING file
Reduce the priority of debugging messages going to the console

These messages are in the normal (non-error) path and add to the
cout/cerr noise.

By default, `cfx run` has its output level set to `info` which
excludes the debug messages. To change this, set the
`extensions.sdk.console.logLevel` pref to `debug` or `all`.

https://developer.mozilla.org/Add-ons/SDK/Tools/console#Logging_Levels
Add a copy of D3's license to comply with it

This is still the same version of D3 (3.2.7) as downloaded from:

  https://github.com/mbostock/d3/releases/tag/v3.2.7
Upgrade D3 to 3.4.6

This is the latest upstream version, available at this URL:

  https://github.com/mbostock/d3/releases/tag/v3.4.6
Add a copy of picoModal's license to comply with it

This is still the same version of picoModal (1.0.0) as downloaded from:

  https://github.com/Nycto/PicoModal/tree/release/release
Remove jQuery and TrackerBlock mentions in the README

We no longer bundle the TrackerBlock JSON file and we no longer
use jQuery.

However, we do bundle PicoModal, so let's add it to the list.
Merge pull request #558 from fmarier/reduce_console_spam

Comment out debugging messages going to the console
Merge pull request #560 from fmarier/fix_js_warnings

Fix js warnings
Merge pull request #563 from fmarier/upgrade_d3

Upgrade D3
Merge pull request #564 from fmarier/picoModal_license

Add a copy of picoModal's license to comply with it
Merge pull request #566 from fmarier/update_README

Remove jQuery and TrackerBlock mentions in the README
Mention another third-party piece of code we use
Add MPL copyright header to all of our files

As per https://www.mozilla.org/MPL/headers/