Added config options for fixity check
Added GetFilesNotCheckedSince()
Set StorageURL and StorageMd5 in merge
Set file.StoredAt when merging data from Fluctus
Fixed name of fixity channel
Added fixity reader
Changed params to ProcessStatusSearch
Fixed build problem in fluctus client test
Return detailed error if io.Copy fails
Added methods to describe whether checksums were available
Deleted fixity reader
Added offset and limit to GetFilesNotCheckedSince
Pass FixityResult into (not out of) FetchAndCalculateSha256
Fixed some tests
Added tests for new FixityResult functions
Build apt_fixity
Added supervisord config for fixity worker