Partial commit, moving the polls out into their own module.

Again, this is part of the refactoring and simplification, so this commit is not fully working. Particularly:

- the viewer in the client still needs to be simplified (adding new kinds of content errors)
- some URLs have changed on the server and have not yet been updated in the client
- some content types have not been tested
- Q&A needs to be moved into its own module, and the client updated for the fact that it is now a content type