Handle errors on submit(raw)

`fs rename` followed by `fs sets --check` (without
a move inbetween) was leading to a `CmdError` being
printed before this change.
Refactor 'tomove' return to contain target

In preparation for also specifying a tomove for the
log file, we need to specify where the file should
be moved *to*, since the log file is a directory up
from the actual fileset.
Also print CmdError on --move
Move log file as well