Don't fetch secrets.json file when the info is already avail from local storage

Test Plan:
- Make sure when info is avail in local storage it works fine.
- Make sure when info is not in local storage it works fine.
New minimized topic tree files with null mp4 videos rmeoved

Test Plan:
- Make sure a known null video no longer appears in topic tree when app
  is launched.
Code to remove and report on null mp4 url videos

Test Plan:
- Run script, spot check against untouched returned topic tree data
Add a contributors section to the README

Test Plan:
- None
Store user data files context sensitive to the current user

Test Plan:
- Make sure freshing doens't always say refreshing user info from server
  each time.
Convert # links to javascript:void operator

Test Plan:
- None
Don't use APIClient directly from main view to log out, use model instead

Test Plan:
- None
User specific info should clear when logged off and not redownload when using different users.

Test Plan:
- Test swatpping between 2 users. Make sure the console messages
  indicate what's goin on with regards to which info is being retrieved..
Add some basic info to the README

Test Plan:
- None