changes to code, commenting and reorganization

1. noticed mistake in parsing the planet and mission
    (off by one) - should be fixed now.
2. switched open() and close() to the with idiom, but
    I need to double check that I'm doing it correctly :P
3. noticed inconsistency in the establishment of the last_id
    that is potentially creating string _id's for a few
    documents in the database. I think I have made them
    consistently integers now, but I need to check that
    it all works
3. lots of commenting and reorganization

unfortunately, because I do not have any test tweets saved
and a debug mode, I can't check that the parsing/database
populating code works unless I also have a connection. And
since I'm on a plane right now and I'm a poor college student
who is not going to pay for gogo inflight wifi, that's not
happening right now.

SO MAKE SURE YOU TEST AND THEN RECOMMIT WITH CHANGES
Renamed newscrape to fetchalerts

also moar comments :D
readme changes

should also move my fixmes etc into the readmes, especially
the ones in the update.sh file. ah well.
fixes to offline commits and some fixme stuff :D