The couch state checks if all user databases have the correct schema
version on initialization, and may log errors and raise exceptions if
that is not the case. Because we are currently using `twistd web
--wsgi`, if those errors are logged too early the reactor may have not
been started and the twistd logging facilities may not have been
initialized.

This commit delays the state initialization until the reactor has been
started, to make sure any errors raised and logged in that stage will
actually reach the logfile.

Conflicts:
	server/src/leap/soledad/server/__init__.py
	testing/tests/conftest.py

When importing server, couch_state will load itself against couch_db url
configured on server. This fails when running on Docker as couchdb is in
another node.

CouchServerState is spread across test codebase and this option is
intended to be used only on server startup. This commit makes it default
to False and explicitly set it to True on where it's necessary.