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/net/src/main/java/org/onlab/onos/net/host/impl/HostManager.java b/core/net/src/main/java/org/onlab/onos/net/host/impl/HostManager.java
index 4f9bcbb..e4d158d 100644
--- a/core/net/src/main/java/org/onlab/onos/net/host/impl/HostManager.java
+++ b/core/net/src/main/java/org/onlab/onos/net/host/impl/HostManager.java
@@ -33,7 +33,6 @@
 import org.onlab.onos.net.provider.AbstractProviderRegistry;
 import org.onlab.onos.net.provider.AbstractProviderService;
 import org.onlab.packet.IpAddress;
-import org.onlab.packet.IpPrefix;
 import org.onlab.packet.MacAddress;
 import org.onlab.packet.VlanId;
 import org.slf4j.Logger;
@@ -121,7 +120,7 @@
     }
 
     @Override
-    public Set<Host> getHostsByIp(IpPrefix ip) {
+    public Set<Host> getHostsByIp(IpAddress ip) {
         checkNotNull(ip, "IP address cannot be null");
         return store.getHosts(ip);
     }
diff --git a/core/net/src/main/java/org/onlab/onos/net/host/impl/HostMonitor.java b/core/net/src/main/java/org/onlab/onos/net/host/impl/HostMonitor.java
index a624c07..e92440f 100644
--- a/core/net/src/main/java/org/onlab/onos/net/host/impl/HostMonitor.java
+++ b/core/net/src/main/java/org/onlab/onos/net/host/impl/HostMonitor.java
@@ -129,10 +129,7 @@
     @Override
     public void run(Timeout timeout) throws Exception {
         for (IpAddress ip : monitoredAddresses) {
-            // TODO have to convert right now because the HostService API uses IpPrefix
-            IpPrefix prefix = IpPrefix.valueOf(ip.toOctets());
-
-            Set<Host> hosts = hostManager.getHostsByIp(prefix);
+            Set<Host> hosts = hostManager.getHostsByIp(ip);
 
             if (hosts.isEmpty()) {
                 sendArpRequest(ip);
diff --git a/core/net/src/main/java/org/onlab/onos/net/proxyarp/impl/ProxyArpManager.java b/core/net/src/main/java/org/onlab/onos/net/proxyarp/impl/ProxyArpManager.java
index 735c109..3ba1c8a 100644
--- a/core/net/src/main/java/org/onlab/onos/net/proxyarp/impl/ProxyArpManager.java
+++ b/core/net/src/main/java/org/onlab/onos/net/proxyarp/impl/ProxyArpManager.java
@@ -99,7 +99,7 @@
     }
 
     @Override
-    public boolean known(IpPrefix addr) {
+    public boolean known(IpAddress addr) {
         checkNotNull(addr, MAC_ADDR_NULL);
         Set<Host> hosts = hostService.getHostsByIp(addr);
         return !hosts.isEmpty();
@@ -150,7 +150,7 @@
         // Continue with normal proxy ARP case
 
         VlanId vlan = VlanId.vlanId(eth.getVlanID());
-        Set<Host> hosts = hostService.getHostsByIp(IpPrefix.valueOf(arp
+        Set<Host> hosts = hostService.getHostsByIp(IpAddress.valueOf(arp
                 .getTargetProtocolAddress()));
 
         Host dst = null;
@@ -170,8 +170,7 @@
         }
 
         // TODO find the correct IP address
-        IpAddress ipAddress =
-            dst.ipAddresses().iterator().next().toIpAddress();
+        IpAddress ipAddress = dst.ipAddresses().iterator().next();
         Ethernet arpReply = buildArpReply(ipAddress, dst.mac(), eth);
         // TODO: check send status with host service.
         sendTo(arpReply, src.location());