Enable checkstyle rule for checking the number of lines of code in a method

Enabled the "MethodLength" checkstyle check and set the maximum
number of lines to 200.

Refactored the add() method in FlowPusher.java to break out some
straight line code into separate methods to get it below
200 lines.

Change-Id: Ib6e2751550921dd7b7a0f184cff57d7a5f19740e
diff --git a/conf/checkstyle/sun_checks.xml b/conf/checkstyle/sun_checks.xml
index d2eea90..60ac173 100644
--- a/conf/checkstyle/sun_checks.xml
+++ b/conf/checkstyle/sun_checks.xml
@@ -148,8 +148,8 @@
           <property name="severity" value="warning"/>
         </module>
         <module name="MethodLength">
-          <property name="severity" value="warning"/>
-        </module>
+	  <property name="max" value="200"/>
+	</module>
 
         <module name="ParameterNumber"/>