removed unnecesary/outdated/unused files

youtube_3_api.py -> API_3_demo.py
----------------
this file won't be needed for too much longer, but is a good demo so why
not keep it around for now.

URLs.txt
----------------
irrelevant.  3.0 API uses the channel ID stuff

YTChannel.py
----------------
ancient and unused.  channels will likely live in the big json dicionary

channels.txt
----------------
useless in new 3.0 youtube API.  'source' options in splatfilch.py
facilitate adding/removal of channels and properly format things too.

connection_test.py
----------------
no need for an entire module for a simple go/no-go test.  this was
inlined into splatfilch.py

extract_tags.py
----------------
probably the oldest file here.  this was from when were were considering
regex as an option for getting video links.  definitely obsolute with
any youtube API

gdata_yt.py
----------------
old youtube 2.0 API, no longer needed

recent_urls.py
----------------
what was this even?
configfile tweaks

- json_config:  datetime format specifier now lives in json_config.  it
  is better to have this centralized, and it was taking up space in the
  main program anyway.

- cachefile: made it executable.  why wasn't it already?

- splatfilch:
    - inlined internet connectivity test and added logging for success
      AND failure
    - added check to ensure that log directory exists
    - reordered program order slightly
    - added feature to prevent a new run if the last one was like 5
      seconds ago.
    - made program update lastrun at the end.  this crucial step seems
      to have been lost at some point.