Moved team registration logic into separate file.
Cleaned up other routes for teams, e.g. login and logout.
Refactored teams module again.

Merged functionality into single object by using `_.extend`.
Refactored graphs module in the same way as teams.

Put each API function into a separate file. Would be nice if defined a
`findById` helper function with a callback since that is commonly done
in each of these members.

Merged functionality into single object by using `_.extend`.
Refactored submissions module in the same way as teams and graphs.

Put each API function into a separate file. Defined a helper module
for the common components of create the Redis key and verifying the
graph exists.

Merged functionality into single object by using `_.extend`.

Also made it so that graph downloads as `x.y.z.json` by default, rather
than the filename as stored on disk if left unspecified.
Changed meaning of default style on submission dashboard.

Now is used to indicate that the graph was not attempted before the end
time, since no record of downloads is kept past that point.