Add coverage
Move location tests to py.test
Add aspects test
Remove old location test
Some testing environment fixes

- remove any config data from an existing indico.conf
- clear all existing loggers
- capture logging messages (shown if a test fails)
- disable caching
- create a global temp dir for indico code (e.g. the cache) needing one

Probably we should get rid of the global temp dir at some point and set
a per-test temp dir from within test cases needing one!