Remove references to 'IPAM' in docs and UI

The option `--no-default-ipam` is replaced with
`--no-default-ipalloc`; the former will still work (in a 'last one
wins' way), but its usage message says it's deprecated.

test/600_proxy_docker_py_test.sh

@@ -6,7 +6,7 @@ start_suite "Run docker-py test suite against the proxy"
 
 docker_on $HOST1 pull joffrey/docker-py >/dev/null
 
-weave_on $HOST1 launch-proxy --no-default-ipam
+weave_on $HOST1 launch-proxy --no-default-ipalloc
 
 if docker_on $HOST1 run \
     -e NOT_ON_HOST=true \

test/660_proxy_ipam_test.sh

@@ -20,7 +20,7 @@ start_suite "Ping proxied containers over cross-host weave network (with IPAM)"
 weave_on $HOST1 launch-router -iprange $UNIVERSE
 weave_on $HOST2 launch-router -iprange $UNIVERSE $HOST1
 weave_on $HOST1 launch-proxy
-weave_on $HOST2 launch-proxy --no-default-ipam
+weave_on $HOST2 launch-proxy --no-default-ipalloc
 
 start $HOST1 --name=auto
 start $HOST1 --name=none       -e WEAVE_CIDR=none