Merge pull request #210 from lukechampine/files

siafiles
unify siblingIndex - now is only in engine struct
find and repair snapshot desynchronization error
address travis empty wallet bug
add verbose option to client-cli
fix blockchain printing bug, introduce non-upload bug
temporary workaround for scratch
add test for upload and download
fix repair bug
fix byte overflow issue in UpdateSectorInput
address PR comments
reduce the number of blocks used during testing
address new PR comments
Merge pull request #212 from DavidVorick/bugscrub

Bugscrub
new scratch implementation
remove bytes.NewReader in update