Re-implement circusweb with tornadoweb

 - Drop gevent
 - Make circus ØMQ call asynchronous
 - Prepare implementation for multi-endpoint simultaneous connections (just need to update templates)
 - Implement multiuser for circusweb
 - Global flake8 compliancy
 - Remove legacy code
Merge pull request #19 from mozilla-services/tornado_rewriting

Re-implement circusweb with tornadoweb
Fix zeromq eventloop installation
Add a session system and fix timeout error on login.

Implement an in memory session system.
Add previous existing messages.
Raise CallError in circus client in order to be able to catch it during connection.
Merge pull request #20 from mozilla-services/pr1

Fix zeromq eventloop installation
Merge pull request #21 from mozilla-services/pr3

Add a session system and fix timeout error on login.
Fix missing fonts.
fixed #23 & #24
Fix reverse_url for switch_status in index.html
Merge pull request #22 from bendemaree/master

Fix missing fonts
Little UI improvment
First implement without graph working
Make it more verbose
Fix graphs
Graphs works with multi-endpoints
Better handling of connections
Fix more problems. Make a all sockets view.
Remove debug and fix watcher last_age span id
Fix title color in watcher and socket list.
Fix PEP8