moved longhair submodule to quorum
move common/erasure to quorum/erasure
remove common package entirely

Conflicts:
	Makefile
	src/client/client.go
	src/client/client_test.go
rename ZeroNetwork to DebugNetwork
underlying keys are no longer exported in siacrypto
refactor siacrypto
move longhair functions to erasure package
move longhair to erasure/longhair

Conflicts:
	Makefile
	src/erasure/longhair
update documentation within erasure package