* lots of changes to the contributing howto from Matt, Greg, Will, and
Chris
* adds references between the contributing howto and other chapters
* adds a design decision regarding copyright assignment
* changes COPYING to explain licensing for all of GNU MediaGoblin
* adds design decision regarding why we picked the licensing we did
* adds CC0 and AGPLv3 texts
* removes licensing bits from hacking howto--we should put that somewhere
else
* fixes some typos
* tweaks some language issues that occured because I took Chris'
stuff out of the context of the original READMEish structure
* ditches installation for deploymenthowto and hackinghowto
use, what their function is, and urls for library documentation
* adds a forward chapter which talks about the documentation
* adds an installation stub
* adds a software stack chapter that covers what libraries are in
* adds a design decisions chapter which covers why we chose the
libraries and architecture
