Enable checkstyle check for blocks without braces.

Enable the checkstyle rule to check for block statements
without curly braces and fix any violations it finds.

Change-Id: Id4c58cea26f0d9ce7ed78643a4943c042886a12d
diff --git a/src/main/java/net/onrc/onos/core/util/IPv4Net.java b/src/main/java/net/onrc/onos/core/util/IPv4Net.java
index 6a04635..3b8fad6 100644
--- a/src/main/java/net/onrc/onos/core/util/IPv4Net.java
+++ b/src/main/java/net/onrc/onos/core/util/IPv4Net.java
@@ -30,10 +30,11 @@
      * @param other the object to copy from.
      */
     public IPv4Net(IPv4Net other) {
-        if (other.address != null)
+        if (other.address != null) {
             this.address = new IPv4(other.address);
-        else
+        } else {
             this.address = null;
+        }
         this.prefixLen = other.prefixLen;
     }