Updating script to use Rdio API and redis storage

So, I got a little crazy with this. I've been looking for an excuse to
try out using redis for key:value storage and CSVs are, like, totally
lame.

Since this is basically just a first pass at this, I did all the fun
stuff in the url parsing loop. Like a crazy person. We'll refactor this
in later revisions.

The comments should explain most of what I changed, with TODOs
describing some of the things I want to add.
Updating script with more features

Here's the second pass at making this a useful script. I gave a lot more
thought to how I wanted to store/query the data this time, and
refactored _most_ of the code out of the rss parsing loop. Also, now
that we're storing the unavailable albums, we can query if they've
become available every time at the end of the script!

I added a key to store the value of the most recently parsed item in the
feed, so we don't even need to look at the whole feed every time. Cool.
Fixing up some indentation/formatting errors
Updating README with more relevant info
Merge remote-tracking branch 'DTAB/master'