- Simplify all imports
- Update dependency version in setup.py
- Change waitTime default from three seconds to two

* Added exclusions module with a fully implemented ExclusionsDB that can pull
  from multiple sources for different sites.
* Moved CopyvioCheckResult to its own module, to be imported by __init__.
* Some other related changes.

Also implementing MWParserFromHell, plus some cleanup.

- In config.json, search config relocated from
  tasks.afc_copyvios to wiki.
- Site.__init__() takes a `search_config' argument, which is
  auto-supplied from its value in config.json by get_site().
- Page.copyvio_check() doesn't ask for search config
  anymore, meaning doing checks from the command line
  is less painful.
- Added a Page.copyvio_compare() function, which works
  just like copyvio_check() but on a specified URL; this is
  for cache retrieval on the web front-end.

- Incomplete; need this for the TS rewrite
- Also starting work on docstrings for some methods

Also removed the hardcoded version in user-agent strings.