Testing Round One

Added some stuff, including:

1. make cover, which produces testing coverage stats for all of our packages that have test files. Eventually all packages should have test files.
2. documentation to the makefile
3. Some organizational stuff
4. A whole bunch of tests for the consensus package, bringing coverage up to 44%. Right now pretty much only empty blocks are tested, which is why the number is so low. No contracts or financial stuff is tested, and the exported functions don't get much love either. That'll be in round two.