FS#runProcess: Fix OutputStream left unclosed after IOException

FS#runProcess: Fix OutputStream left unclosed after IOException

The runProcess method creates an OutputStream that is not managed by
a try-with-resource because it's manually closed and any IOException
raised by the close() method is explicitly ignored.

Suppress the resource warning with an explanatory comment.

Enclose the call to StreamGobbler#copy in an inner try-block, and move
the call to close() inside its finally block. This prevents the stream
from being left unclosed if StreamGobbler#copy raises IOException.

Change-Id: Idca9adfc4d87e0989d787ad8239c055c0c849814
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>