Python 3 fix to tests
Dogfood
Mock != rspec-mocks, 1st arg is not name
Reorder an import
Use real Sphinx app/config objs to catch high level config errors.

Requires awful hacks to work around Sphinx untestability =/
Flesh out test so it passes/fails correctly
Refactor assertions & add failing test re: changelog name
DDD and TDD re: new setting
Implementation. Fixes #22.
Changelog re #22
Merge branch 'better-tests-also-configurable-filename'

Conflicts:
	tests/changelog.py