Refactor content requirements.

[thyrgle]

Currently, the needlemanwunsh.py content method requires too much knowledge on the part of the programmer trying to create problems, more work should be delegated to the problems.py using a decorator or something of the sort. Specifically:

1. There is no need to handle post requests.
2. The templates file should not require the problem programmer to import scripts for problem loading, this should be done for them.
3. There might be the need for some matrix helpers to load from HTML? This part of the API is still up in the air... (More specifically, the matrices differ vastly in internal structure, is there a clean way to encapsulate all of them?)

[thyrgle]

This is now "done", but I am leaving this open for now as I should probably make the manage_content (pseudo-)decorator cleaner.