Replaced IpPrefix and IpAddress in the following methods
and cleanup related code:

 - Host.ipAddresses()
 - DefaultHost.ipAddresses()
 - HostDescription.ipAddress()
 - DefaultHostDescription.ipAddress()
 - HostService.getHostsByIp()
 - HostManager.getHostsByIp()
 - HostStore.getHosts()
 - GossipHostStore.getHosts()
 - SimpleHostStore.getHosts()
 - ProxyArpService.known()
 - ProxyArpManager.known()

As a result of the above cleanup, the "hosts" CLI command outputs
the IP addresses as "1.2.3.4" instead of "1.2.3.4/32".

Also, the following REST calls might be affected as well with
the above format replacement:
  - REST POST: config/topology
  - REST GET: topology/graph
diff --git a/core/api/src/test/java/org/onlab/onos/net/TestDeviceParams.java b/core/api/src/test/java/org/onlab/onos/net/TestDeviceParams.java
index d24e1c8..7471a2d 100644
--- a/core/api/src/test/java/org/onlab/onos/net/TestDeviceParams.java
+++ b/core/api/src/test/java/org/onlab/onos/net/TestDeviceParams.java
@@ -5,7 +5,7 @@
 import java.util.Set;
 
 import org.onlab.onos.net.provider.ProviderId;
-import org.onlab.packet.IpPrefix;
+import org.onlab.packet.IpAddress;
 import org.onlab.packet.MacAddress;
 import org.onlab.packet.VlanId;
 
@@ -24,9 +24,9 @@
     protected static final MacAddress MAC2 = MacAddress.valueOf("00:22:00:00:00:02");
     protected static final VlanId VLAN1 = VlanId.vlanId((short) 11);
     protected static final VlanId VLAN2 = VlanId.vlanId((short) 22);
-    protected static final IpPrefix IP1 = IpPrefix.valueOf("10.0.0.1");
-    protected static final IpPrefix IP2 = IpPrefix.valueOf("10.0.0.2");
-    protected static final IpPrefix IP3 = IpPrefix.valueOf("10.0.0.3");
+    protected static final IpAddress IP1 = IpAddress.valueOf("10.0.0.1");
+    protected static final IpAddress IP2 = IpAddress.valueOf("10.0.0.2");
+    protected static final IpAddress IP3 = IpAddress.valueOf("10.0.0.3");
 
     protected static final PortNumber P1 = PortNumber.portNumber(100);
     protected static final PortNumber P2 = PortNumber.portNumber(200);
@@ -34,7 +34,7 @@
     protected static final HostId HID2 = HostId.hostId(MAC2, VLAN2);
     protected static final HostLocation LOC1 = new HostLocation(DID1, P1, 123L);
     protected static final HostLocation LOC2 = new HostLocation(DID2, P2, 123L);
-    protected static final Set<IpPrefix> IPSET1 = Sets.newHashSet(IP1, IP2);
-    protected static final Set<IpPrefix> IPSET2 = Sets.newHashSet(IP1, IP3);
+    protected static final Set<IpAddress> IPSET1 = Sets.newHashSet(IP1, IP2);
+    protected static final Set<IpAddress> IPSET2 = Sets.newHashSet(IP1, IP3);
 
 }