this implements the rm command which has to add
a Remove method to the fileystem interface and
implement it for local, remote and test filesystems.
Change-Id: Id41add28f01938893530aae0b4b73c8954e9b715
this adds some stuff to ultest so that the set of
files created by a test can be inspected after so
that we can write some tests for the cp command
to observe that it does what it is supposed to do.
Change-Id: I98b8fb214058140dfbb117baa7acea6a2cc340e1