telemeta/management/commands/telemeta-media-analyze.py: rename option to --force, import time in case
telemeta/views/item.py: remove all existing fields if force == True
INSTALL.rst: talk about telemeta-media-analyze
telemeta/views/item.py: use results if available
INSTALL.rst: lists not tuples
telemeta/management/commands/telemeta-media-analyze.py: improve output