Basic infrastructure for terminal page
Terminal basically working

Still need to deal with things like authentication
Multiple terminals and conditional initialisation
Initial REST API for terminals
Add authentication for terminal websockets
Put terminal handlers under base_url
Don't load html.terminal for tests if terminado not installed
Use relative URL for redirect in NewTerminalHandler
Add term.js to package data for installation.
recompute dummy size dynamically + styling in css
HTML fix
Add mention of terminals in whatsnew
Add comment explaining 1.02 factor
Move terminal CSS into LESS file
Compatibility fix for Tornado 3.x
Remove override.css from the template
Update components to master AGAIN. Sodding git submodules
Merge pull request #6614 from takluyver/nb-terminal-ui

Terminal emulator in the notebook