Enable checkstyle rule to check for boolean simplifications

Enable the checkstyle "SimplifyBooleanExpression" rule and
fix any violations it reports.

Change-Id: If8a0226829da3339b9209324a8ea36a28f2138c4
diff --git a/src/main/java/net/onrc/onos/core/flowprogrammer/FlowPusher.java b/src/main/java/net/onrc/onos/core/flowprogrammer/FlowPusher.java
index 56e4231..0bcb001 100644
--- a/src/main/java/net/onrc/onos/core/flowprogrammer/FlowPusher.java
+++ b/src/main/java/net/onrc/onos/core/flowprogrammer/FlowPusher.java
@@ -835,7 +835,7 @@
             }
 
             if (actionStripVlan != null) {
-                if (actionStripVlan.stripVlan() == true) {
+                if (actionStripVlan.stripVlan()) {
                     OFActionStripVirtualLan ofa = new OFActionStripVirtualLan();
                     openFlowActions.add(ofa);
                     actionsLen += ofa.getLength();