Cmd line args

Richard,

Saw today you have made some recent updates to A-vs-B - i've synced my fork with those changes and then added in my own ones. This pull request is basically so you can check them out, see if you like em, and merge if you want.

- added in the argparse module for both scripts, and set up the script so it asks for args when run from cmd line. Slightly easier to input different GTFS, db paths in my opinion, rather than having to edit the script (can just drag and drop from finder / windows)
- changed the text_factory to str, rather than optimized unicode. Reading the docs optimized seems better, but it's what is causing the script to crash for me, and I'm guessing most GTFS don't have non-ASCII characters (and if they do, i think str still works?)
- changed the script to look for ".txt" rather than ".txt.". I'm guessing your GTFS copy has all the files with .txt. for some reason - not sure why that would be, the Wellington and Auckland ones I have are just .txt as you'd expect.

Created a topic branch for the request, so I can make changes if need be.
No offense at all if you want to maintain your repo yourself :+1: