Add gitignore & format README w/ markdown

[mlippert]

William, You may not want this at all, but I felt it was an improvement so I'm submitting a pull request so you can check it out.

All I've done is:

1. added a .gitignore starting w/ the base python gitignore from github and adding pytivo.conf and the bin folder.
2. converted your README to README.md in markdown syntax which github will format and display when viewing the repository. Then I made a few additional small tweaks to the README adding some info from the wiki and some links.
3. lastly because I wasn't sure that the HMO spec would be available forever, I copied it into the doc subfolder. I'm still trying to figure out what a GoBack server is because I'd like to add a link to that as well.

If you like the changes please merge them if not I won't be offended if you close this pull request w/o merging.