New methods have been added to TestPMDShell in order to produce the mac
filter's individual test cases:
 - set_mac_addr
 - set_multicast_mac_addr

set_mac_addr and set_multicast_addr were created for the mac filter test
suite, enabling users to both add or remove mac and multicast
addresses based on a boolean 'add or remove' parameter. The success or
failure of each call can be verified if a user deems it necessary.

Bugzilla ID: 1454
Signed-off-by: Nicholas Pratte <npratte@iol.unh.edu>