Ignore compiled valo test themes

Valo is not included in 7.2, but it still helps to have the generated
resources ignored when changing between branches.

Change-Id: I4f2580230a18adf299334eb43aea4f8bccd7bb4a

.gitignore

@@ -40,6 +40,10 @@
 /WebContent/VAADIN/themes/runo/common/img/ajax-loader-red.gif
 /WebContent/VAADIN/themes/runo/common/img/ajax-loader-yellow.gif
 
+# /WebContent/VAADIN/themes/valo/
+/WebContent/VAADIN/themes/valo/styles.css
+/WebContent/VAADIN/themes/tests-valo*/styles.css
+
 # /WebContent/VAADIN/widgetsets/
 /WebContent/VAADIN/widgetsets
 /WebContent/VAADIN/gwt-unitCache*