Add SiaRandomNumber

Quick fix on the Makefile, entropy_test.go reduced to 1 function, struct
State removed and all variables added to struct Blockchain. Every piece
of the entropy process should be complete at this point.
Resolved merge conflict
Merge branch 'master' of github.com:Siacoin/Sia
Send NodeAlive in the StateSwarmInformed correctly
Added HeartbeatTransaction and related functions
Merge github.com:c00w/Sia into Heartbeat

Conflicts:
	src/swarm/swarm.go
Added unmarshaling ability to HeartbeatTransaction
MarshalString for HeartbeatTransaction now uses MarshalTransaction.
Modified UnmarshalTransaction to recognize the HeartbeatTransaction
struct (using "Heartbeat" as a temporary identifier, change if
confusing).
Fixed syntax errors
StateSwarmInformed Figures out if it should generate a block
Merge branch 'master' of github.com:c00w/Sia into Heartbeat
Merge pull request #11 from DavidVorick/master

Add SiaRandomNumber
Merge branch 'master' of github.com:Siacoin/Sia

Conflicts:
	src/swarm/swarm.go
Generate an initial block and accept initial blocks
Merge branch 'master' of github.com:c00w/Sia into Heartbeat

Conflicts:
	src/swarm/swarm.go
Store blocks in blockchain
Merge branch 'master' of github.com:c00w/Sia into Heartbeat
Started StateSteady, minimally functional
Merge branch 'master' of github.com:Siacoin/Sia

Conflicts:
	src/swarm/swarm.go
Merge branch 'Heartbeat'

Conflicts:
	src/swarm/swarm.go