retry if internet drops out briefly
saves errors to a db
Merge branch 'master' into feature/db

Conflicts:
	bigappleserialbus.py
	busstop.py
preliminary stuff for saving trajectories to db
almost works saving trajectories; working on interpolatoin
successfully write trajectories to the db
Merge branch 'master' into feature/db
it appears to work
assorted cleanup and reorg
clustering bit works.
clustering by trajectory (no temporal features yet)
add comment
Merge branch 'master' into feature/db

Conflicts:
	busstop.py
better error handling