Remove submodule user-management

  Removed the user management code as a sub-module and made it part of
swtstore. The relevant files are under classes/models directory.
Two reasons for doing this:
  - user management code has started to become swtstore specific.
  - setting up of swtstore becomes easier.
Update code after removing submodule

  Updated the code to work w/o user management submodule.
This removes cloning the sub-module separately and configuring it.
Add timestamp format at server-side; code consistency at views

  - Decided to moment.js but later. Until then, the to_dict method of sweet and
    user returns formatted date in UTC.
  - Making all sweet and user related views to use the to_dict method and be
    consistent
Merge branch 'dev' of github.com:janastu/swtstore into dev
Fix dbsetup.py after removing submodule

  After removing the submodule, fix the import statement in dbsetup.py