Reorganize settings files for different environments

Revert "Use git to get the branch name and commit number, rather than incoming environment variables"

This reverts commit d6a57558.

Catch Exception instead of ValueError for accessing our general content cache -- exception thrown changed in django 1.4

Fixed zero-score-possible bug.

fixed the default weight to not interfere with precedent

added weighting system for the midterm

It'd be nice to move the Score.__sub__ as we discussed, but that shouldn't hold up merging the rest so it can be put on the staging environments and tested more thoroughly.

Pmitros/histogram