Added sublime files to gitignore.
Fixed bad serialization in submission model.

* Fixes #215.
* This fix was first applied via a monkey-patch on legion.
Merge branch 'v0.2dev' of github.com:galah-group/galah into v0.2dev
Added debug flag to create_admin utility.
Fixed default value in modify_assignment.

* Fixes #206.
* True or False must be entered exactly (case insensitve) or a user
  error is raised.
get_csv produces empty CSV if no matches.

* Fixes #218.
* For now the idea should be to keep sisyphus from failing until we
  find a way to serve errors to the user in a reliable way.
get_csv no longer balks on empty results.

* Fixes #217.