Moved staging functions into submissions.py.

Changed
=======

* Functions to stage a model simulation are now in submissions.py. This
  stuff used to be in wmt/run.py.
Fixed bug where the old site setup directory was used.
Added new module utils/time.py to hold some time utility functions.
Moved utility functions into utils sub-package.
Added stage_dir to submissions table.

Added
=====

* A sumbission entry now hold the path to it's staging directory.
Changed run/stage command to take uuid as part of its query string.
Added validators for valid UUIDS and check for submission existance.
Added FontAwesome styling.