IpAddress and IpPrefix related cleanup:
 * Removed IpAddress.MAX_INET_MASK and use IpPrefix.MAX_INET_MASK_LENGTH
   instead
 * Renamed IpAddress.INET_LEN to INET_BYTE_LENGTH
 * Added IpAddress.INET_BIT_LENGTH, INET6_BYTE_LENGTH, and INET6_BIT_LENGTH
 * Removed methods that are semantically incorrect, or are not needed/used
   - IpAddress.prefixLength()
   - IpAddress.toPrefix()
   - IpAddress.mask()
   - IpAddress.netmask()
   - IpAddress.network()
   - IpAddress.host()
   - IpAddress.isMasked()
   - IpAddress.contains()
   - IpPrefix constructor for version and bytes (but no netmask)
   - IpPrefix.valueOf(int)

 * Misc. other cleanup.
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 cfe4749..4b12931 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
@@ -46,7 +46,6 @@
 import org.onlab.packet.ARP;
 import org.onlab.packet.Ethernet;
 import org.onlab.packet.IpAddress;
-import org.onlab.packet.IpPrefix;
 import org.onlab.packet.MacAddress;
 import org.onlab.util.Timer;
 
@@ -212,7 +211,7 @@
         arp.setHardwareType(ARP.HW_TYPE_ETHERNET)
            .setHardwareAddressLength((byte) Ethernet.DATALAYER_ADDRESS_LENGTH)
            .setProtocolType(ARP.PROTO_TYPE_IP)
-           .setProtocolAddressLength((byte) IpPrefix.INET_LEN)
+           .setProtocolAddressLength((byte) IpAddress.INET_BYTE_LENGTH)
            .setOpCode(ARP.OP_REQUEST);
 
         arp.setSenderHardwareAddress(sourceMac.getAddress())