Make tests run in memory

Conflicts:

	daybed/backends/couchdb/backend.py
	daybed/backends/couchdb/database.py
	daybed/tests/support.py
	daybed/views/data.py
	tests.ini
Fix memory backend Database comment
Move backend common code to app init

Conflicts:

	daybed/__init__.py
	daybed/backends/memory/backend.py
Upgrade code of MemoryBackend to new interfaces
Merge pull request #83 from spiral-project/add_memory_backend

Add memory backend (fixes #107)