java: Fix argument splitting in MultiJarLoader

MultiJarLoader reads the command line parameters from a file
and uses split to make a list of params out of them before
calling parseArgs.

Currently the regular expression is \\s which means that
consecutive space will be split it to an empty string.
It should be \\s+ so consecutive spaces will be ignored.

Found by code inspection.

Reviewed-by: Nadav Har'El <nyh@cloudius-systems.com>
Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>