Add unofficial_api_test user account

Subscribed to one camera: the Richmond Zoo Cheetah Cam. Adorable!
Make time-lapses less jerky

Add intermediate frames (default of 1 frame per 15 minutes) between
detected motion events.
Make time-lapses less jerky, fix test filename
Better error handling for API requests
Add API for Dropcam DPTZ (Zoom/Enhance)

To zoom 4x into the center of the field of view:
    my_camera.set_dptz(width=0.25, height=0.25)

To zoom 10x into the right edge of the field of view:
    my_camera.set_dptz(width=0.1, height=0.1, center_x=0.9)