Added a signum to the SetMetaDataMask BigInt constructor

-OF TestCommandProvider doesnt appear functional atm, but
I did test the Java API calls from elsewhere. The test
function should now work. Below is the instantiated flowmod:
(Match) metadata=0x100/0xffffff0000000101 actions=drop

Signed-off-by: Brent Salisbury <brent.salisbury@gmail.com>
Merge "Added a signum to the SetMetaDataMask BigInt constructor"