Fix Bug 2290 (try #2)

Ensure that isIPInUse, getLowAddr, allocateIP, releaseIP,
gatewayIP_Pool_overlap and initDefaults are all V6 friendly.

Manual rebase to fix author's abject stupidity...

Change-Id: I5a136e337672f4ad1b71aa42a3fd33a4e5a85aa2
Signed-off-by: Ryan Moats <rmoats@us.ibm.com>
Merge "Fix Bug 2290 (try #2)" into stable/helium