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/host/DefaultHostDecriptionTest.java b/core/api/src/test/java/org/onlab/onos/net/host/DefaultHostDecriptionTest.java
index 2cd0edc..ec58b16 100644
--- a/core/api/src/test/java/org/onlab/onos/net/host/DefaultHostDecriptionTest.java
+++ b/core/api/src/test/java/org/onlab/onos/net/host/DefaultHostDecriptionTest.java
@@ -4,7 +4,7 @@
 import org.onlab.onos.net.DeviceId;
 import org.onlab.onos.net.HostLocation;
 import org.onlab.onos.net.PortNumber;
-import org.onlab.packet.IpPrefix;
+import org.onlab.packet.IpAddress;
 import org.onlab.packet.MacAddress;
 import org.onlab.packet.VlanId;
 
@@ -20,7 +20,7 @@
 
     private static final MacAddress MAC = MacAddress.valueOf("00:00:11:00:00:01");
     private static final VlanId VLAN = VlanId.vlanId((short) 10);
-    private static final IpPrefix IP = IpPrefix.valueOf("10.0.0.1");
+    private static final IpAddress IP = IpAddress.valueOf("10.0.0.1");
 
     private static final HostLocation LOC = new HostLocation(
             DeviceId.deviceId("of:foo"),
diff --git a/core/api/src/test/java/org/onlab/onos/net/host/HostEventTest.java b/core/api/src/test/java/org/onlab/onos/net/host/HostEventTest.java
index 92a5718..561b041 100644
--- a/core/api/src/test/java/org/onlab/onos/net/host/HostEventTest.java
+++ b/core/api/src/test/java/org/onlab/onos/net/host/HostEventTest.java
@@ -11,7 +11,7 @@
 import org.onlab.onos.net.HostLocation;
 import org.onlab.onos.net.PortNumber;
 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;
 
@@ -27,9 +27,9 @@
                     PortNumber.portNumber(100),
                     123L
                 );
-        Set<IpPrefix> ipset = Sets.newHashSet(
-                    IpPrefix.valueOf("10.0.0.1"),
-                    IpPrefix.valueOf("10.0.0.2")
+        Set<IpAddress> ipset = Sets.newHashSet(
+                    IpAddress.valueOf("10.0.0.1"),
+                    IpAddress.valueOf("10.0.0.2")
                 );
         HostId hid = HostId.hostId(mac, vlan);
 
diff --git a/core/api/src/test/java/org/onlab/onos/net/host/HostServiceAdapter.java b/core/api/src/test/java/org/onlab/onos/net/host/HostServiceAdapter.java
index 2394302..a8085eb 100644
--- a/core/api/src/test/java/org/onlab/onos/net/host/HostServiceAdapter.java
+++ b/core/api/src/test/java/org/onlab/onos/net/host/HostServiceAdapter.java
@@ -7,7 +7,6 @@
 import org.onlab.onos.net.Host;
 import org.onlab.onos.net.HostId;
 import org.onlab.packet.IpAddress;
-import org.onlab.packet.IpPrefix;
 import org.onlab.packet.MacAddress;
 import org.onlab.packet.VlanId;
 
@@ -41,7 +40,7 @@
     }
 
     @Override
-    public Set<Host> getHostsByIp(IpPrefix ip) {
+    public Set<Host> getHostsByIp(IpAddress ip) {
         return null;
     }