Rename our CSS to encourage caching

By using ".cache.css" as our CSS suffix browsers can aggressively
cache this rather large content locally, but we need to keep track
of the version number ourselves anytime we make edits.

Signed-off-by: Shawn O. Pearce <sop@google.com>

src/main/java/com/google/gerrit/Gerrit.gwt.xml

@@ -12,7 +12,7 @@
 
 
   <entry-point class='com.google.gerrit.client.Gerrit'/>
-  <stylesheet src='Gerrit.css' />
+  <stylesheet src='gerrit1.cache.css' />
 
   <servlet path='/Gerrit'
            class='com.google.gerrit.server.HostPageServlet'/>