Use more worker threads for widgetset compilation

Change-Id: Ib7ea54e7a06516acbd9cf3dd08dbbacaac2030f9

client-compiled/build.xml

     <target name="compile-module">
         <fail unless="module" message="You must give the module to compile in the 'module' parameter" />
         <property name="style" value="OBF" />
-        <property name="localWorkers" value="2" />
+        <property name="localWorkers" value="6" />
         <property name="extraParams" value="" />
 
         <ivy:resolve log="download-only" resolveid="common" conf="compile-module" />

uitest/build.xml

     <target name="testing-widgetset" depends="dependencies,compile">
         <property name="module" value="com.vaadin.tests.widgetset.TestingWidgetSet" />
         <property name="style" value="OBF" />
-        <property name="localWorkers" value="2" />
+        <property name="localWorkers" value="6" />
         <property name="extraParams" value="" />
         <property name="module.output.dir" location="${result.dir}/VAADIN/widgetsets" />
         <property name="work.dir" location="${result.dir}/work" />