Setup a nice py.test environment

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!
Prevent SMTP/ZODB connections during tests
Add coverage
Create app error
Adapt tests to the new database
Move location tests to py.test
Add aspects test
Remove old location test
Don't recurse into htdocs
Add tests for (non)bookable hours/periods
Remove empty/obsolete old testcases
Test for non-existant owner, fix mock avatarholder
Parametrize room test, improve dummy_room

also get rid of class wrapping room tests
Flush DB after setting attribute value
Improve test fixtures

- add create_room_attribute
- add create_equipment_type
- add bool_flag
- improve parameters of create_location
Improve location tests
wip room tests
Test Room.kind and remove unnecessary checks
align test params
Properly parametrize test_full_name