Tub view (#129)

* --tub is now optional for train subcommand. It also takes comma-separated format

* new train docopt parameters

* ... causes wierd behavior in docopt

* Tornado server runs with views and apis

* Play tub as video stream now

* Split clips and mark to delete works

* Select clip to play

* Affix preview to the top. UI fine tunes

* API to delete checked clips

* UI finish-up

* Final UI tweakings and minor UI bugs.

* rewind button

* playback speed options

* fix the problem of jumpping affix div

* hot keys

* disable submit button while submitting to improvie usability

* car.py -> manage.py

* steering bar

* add neutrual marker at center of steering bar