fix screen text, allow login in enospc, s3 methods

- allow login if restoring backup fails due to no space left on device
- fix gdrive sync screen text
- s3 methods for deleting and moving files
periodically collect useful system stats

Cluster leader would periodically call different JuliaBox modules
to calculate any interesting statistics and record them in a table.
Collected stats can be used in reports.
admin screen reorganization

to show collected statistics.
also moved some of the earlier data sections to the new scheme.
Merge pull request #155 from tanmaykm/tanmaykm

stats collection and admin screen reorganization, miscellaneous fixes