api: Stop using GetPublicIP in leader.go
api: Stop using GetPublicIP in leader.go

The utility function isn't particularly useful, and in future patches
this call of it will cause an import cycle.

kelda/kelda,quilt/quilt,quilt/quilt,NetSys/quilt,kelda/kelda,quilt/quilt,NetSys/quilt,kelda/kelda,LuiseV/quilt,LuiseV/quilt,NetSys/quilt,LuiseV/quilt,NetSys/quilt,NetSys/quilt,quilt/quilt,kelda/kelda,LuiseV/quilt,LuiseV/quilt