Added metadata match/instructions to md openflow utils

Added metadata match/instructions to md openflow utils

-Flowmod produced as follows:
metadata=0x14,dl_type=0x88cc actions=CONTROLLER:65535,write_metadata:0xc/0xc

- Added a missing instrucionbuilder.build() for a few of
the instructions to add after action builders to the
instruction being returned for the ARP related methods.

The mask on the instruction I beleive is optional but
I am seeing null pointers w/o it. It is marked with a
todo to investigate further but this should satisfy
what we need short term.

Signed-off-by: Brent Salisbury <brent.salisbury@gmail.com>