Use font-stack over installing web fonts

Now using Helvitica Neue/Arial and Georgia over Open Sans and
Merriweather to reduces the size of the application payload and increase
loading times. The fonts themselves were not adding much to the overall
experience.
Remove font adjustment on blockquotes
Remove placeholder on activation code input
Remove Google Font stylesheet
Tweak font stack for Ubuntu
Merge pull request #1476 from hypothesis/remove-web-fonts

Remove web fonts
Remove camelCase from streamer.py

clientID was camelCase. It is now renamed to client_id
Merge pull request #1482 from hypothesis/streamer-remove-camel-case

Remove camelCase from streamer.py
Fix error when pressing delete in empty tag field

Pressing backspace in the tags input still calls the removeTag handler.
This results in an exception when scope.model.tags was undefined. Now
we check for a tag and the tags array before updating.
Remove source map code from vendor files

This removes a huge dump of console warnings as the browser tries and
fails to request the map files.
Merge pull request #1489 from hypothesis/delete-empty-tag

Fix error when pressing delete in empty tag field
Merge pull request #1488 from hypothesis/remove-source-map-warnings

Remove source map code from vendor files
Add unicode normalization for page search
Unicode normalization for stream backend
Unicode normalization for ES
Unit test for string-helpers
Unit tests for FilterToElasticFilter