Update schema to support item service.

TODO Create a script for running migrations.
Implement items service.
Add pyyaml to dependency.
Lazy load `common.dispatcher`. Avoid cyclic import.
Add simple & buggy (maybe) param style pattern support.

Example:

    @dispatcher.reg('match_int_<int:id>')
    def my_callback(request, data, id):
        id = int(id)  # Should not failed here.
Update patterns in group registering.
Change `warn` to `warning`.
Add constants.
Add simple items stats generator.
Add makefile runner.
Implement item persistence support.
Add items configuration.
Refactory items logic.
Implement state logging support.
Fix None function wrapper.

Should return original function after decorating it.
Fix default value of datetime fields.
Add exception format helper.
Add more hints to log for debugging.
Make exception more readable.
Add logging list support.