Tweaked the README to be a bit more friendly and detailed

I thought the README could use some love, so I added some details about licensing and also detailed out procedures for downloading and building the project.

In addition I added a bit to the "What do you get" paragraph and tried to tighten it all up some.
Keep in mind that people who download this aren't necessarily up on what licenses are what. I added the summary there so people would have some knowledge of what they're getting into - the blurb I wrote here reflects this passage:

> You must cause any modified files to carry prominent notices stating that You changed the files; 

In terms of what your lawyers will like - that's MS speak :). I don't think we need to throw LCS at each other for a change to a README... do we?