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/apps/sdnip/src/test/java/org/onlab/onos/sdnip/RouterTestWithAsyncArp.java b/apps/sdnip/src/test/java/org/onlab/onos/sdnip/RouterTestWithAsyncArp.java
index c2e2019..d1c8b2a 100644
--- a/apps/sdnip/src/test/java/org/onlab/onos/sdnip/RouterTestWithAsyncArp.java
+++ b/apps/sdnip/src/test/java/org/onlab/onos/sdnip/RouterTestWithAsyncArp.java
@@ -184,7 +184,7 @@
 
         // Set up test expectation
         reset(hostService);
-        expect(hostService.getHostsByIp(anyObject(IpPrefix.class))).andReturn(
+        expect(hostService.getHostsByIp(anyObject(IpAddress.class))).andReturn(
                 new HashSet<Host>()).anyTimes();
         hostService.startMonitoringIp(IpAddress.valueOf("192.168.10.1"));
         replay(hostService);
@@ -203,7 +203,7 @@
                 new HostLocation(
                         SW1_ETH1.deviceId(),
                         SW1_ETH1.port(), 1),
-                        Sets.newHashSet(IpPrefix.valueOf("192.168.10.1/32")));
+                        Sets.newHashSet(IpAddress.valueOf("192.168.10.1")));
         internalHostListener.event(
                 new HostEvent(HostEvent.Type.HOST_ADDED, host));
 
@@ -266,7 +266,7 @@
 
         // Set up test expectation
         reset(hostService);
-        expect(hostService.getHostsByIp(anyObject(IpPrefix.class))).andReturn(
+        expect(hostService.getHostsByIp(anyObject(IpAddress.class))).andReturn(
                 new HashSet<Host>()).anyTimes();
         hostService.startMonitoringIp(IpAddress.valueOf("192.168.20.1"));
         replay(hostService);
@@ -286,7 +286,7 @@
                 new HostLocation(
                         SW2_ETH1.deviceId(),
                         SW2_ETH1.port(), 1),
-                        Sets.newHashSet(IpPrefix.valueOf("192.168.20.1/32")));
+                        Sets.newHashSet(IpAddress.valueOf("192.168.20.1")));
         internalHostListener.event(
                 new HostEvent(HostEvent.Type.HOST_ADDED, host));