Merge pull request #109 from DavidVorick/demofix

Fix a few panics, demo works again
Merge pull request #110 from DavidVorick/demofix

Re-add basic HandleSignedHeartbeat test
Merge pull request #111 from DavidVorick/demofix

Concensus tests, break bootstrap into it's own file
Merge branch 'master' of github.com:Siacoin/Sia into demofix