virtManager: Convert to CSS for most color usage

* Add CSS data in config.py and install it
* Strip out all hardcoded colors and use style class annotations
* Fix colors to be more theme appropriate to fix dark theme look

Signed-off-by: Cole Robinson <crobinso@redhat.com>

virtManager/hoststorage.py

@@ -51,7 +51,7 @@ def _get_pool_size_percent(pool):
         per = 0
     else:
         per = int(((float(alloc) / float(cap)) * 100))
-    return "<span size='small' color='#484848'>%s%%</span>" % int(per)
+    return "<span size='small'>%s%%</span>" % int(per)
 
 
 class vmmHostStorage(vmmGObjectUI):