use gob instead of manual marshalling

this removes the need for messaging tests
update client to use gob
Merge pull request #98 from lukechampine/node

Switch messaging marshalling to gob
initialize TCPServer struct directly
add rpcnetwork
add data package

the data package contains structs and methods for sectors and
segments, as defined in #67.
move client to RPC
use common/data in client
move data to common
use Sector in erasure
update client for new encoding API
use []byte in place of string
move encoding params to Ring
update client for new Ring
update erasure for new Ring
add unique identifier to RPC service
update client for new RPC
standardize Id -> ID
Merge pull request #99 from lukechampine/rpc

RPC and Sectors