Fixed API to work with new submit model.

Fixed a lot of issues with the api.
Made json serialization standardized.
Fixed a bunch of pylint messages.
Other random things.
Removed old TODO
Fixed travis.
Merge pull request #40 from Cal-CS-61A-Staff/fix_travis

Fixed travis.
Merge branch 'master' into submit-model
Fixed lookup assignments by name.
Update documentation and add TODOs to ok.py
Remove user-specific state from ok.py. Change protocol interface based on examples.
Add command-line options that are easier to understand.
Add -q and -v options
Add assignment inspection to ok.py
Placeholder files for demo assignments
Add content to demo assignment.
Change os.exit to exception
add server option
merge and fix error messages