Merge pull request #205 from DavidVorick/updates

Uploads and Downloads
Merge pull request #206 from DavidVorick/proofofstorage

Proof of Storage
use StorageProof in buildProof and foldHashes
get expectedHash from SectorSettings
Merge pull request #207 from lukechampine/pos

proof-of-storage changes
Merge branch 'master' into autorepair