tree bf626b29ec9bd5e760c0c9e82856920ff00e8abf
parent 7d61ab221090159fd701fbee7d0d5707cf752b38
author Bob Lantz <rlantz@cs.stanford.edu> 1465869424 -0700
committer Bob Lantz <rlantz@cs.stanford.edu> 1465879225 -0700

add arp cmd; always return lists from checkLog

The arp CLI command sends gratuitous ARPs from all hosts - this
makes it easier for ONOS to discover hosts.

Previously checkLog returned None, None if the log file didn't
exist; now we return an empty list, to avoid breaking when we
take the len() of errors or warnings (which was happening before)
and to avoid having to check for None, None, which didn't seem to
add a lot of value to justify its complexity.

Change-Id: I84847fcf70525c82ac037d8a84cf40d21ab2a106