Enabling a fast simple creator without timetable

[prhod]

I think we could use a simplification of the creation of a new creator by allowing the generation of a GTFS without any trips, calendar or stop_times with the default creator and only a config file. (I think @nlehuby talked about that with @xamanu in a comment a few days ago).
I think it could be usefull for new users of osm2gtfs when working on a new creator for a city, or just to extract OSM Transit data for simple analysis in QGIS.

[nlehuby]

I think it would be even better if it creates a valid GTFS, with all files, but with dumb schedules (one trip per route & +1min between each stops, or so).

The trips and stop_times are interesting too when working on a new creator, because they list the stops in the right order for each route.

[nlehuby]

We could have this by implementing #146 and add dumb default values (if not set in OSM).
For instance:

• interval = 12:00
• opening_hours = Mo 08:00-20:00
• duration = 01:00

[pantierra]

I like the idea. We just should pay attention to not remove important functionality. IMHO we would need a way to select the different standard creators from the command line. There I could think about different solutions (let the user select, select on the availability of input etc).