Additional structural changes, to make room for uploading
break synchronize.go into synchronize.go and api.go
yet another reorg of the upload process
purge ResizeSector
begin yet another rehash of the upload function
Merge branch 'master' into review

Conflicts:
	src/state/upload.go
fix all things upload in the delta package
Initial reorg of state for sector updates.
change from using hash to using counter as id
make siacrypto/random smaller and faster
simplify buildProof using SectionReader
add support for placing updateAdvancements into blocks
add support for advancing uploads from the state
except for mis-layering of eventlist, uploads are functional
reimplement MerkleCollapse recursively
switch back to ReadSeeker in buildProof

...plus various other touchups
cleanup erasure and improve error handling
reformat addresses as {host port id}
better comments in network package
add comments to siaencoding package