Copy theme during remote edit.

Fixes: https://launchpad.net/bugs/864822

openlp/core/lib/serviceitem.py

@@ -364,6 +364,9 @@ class ServiceItem(object):
         """
         self._uuid = other._uuid
         self.notes = other.notes
+        # copy theme over if present.  Assumes overridden
+        if other.theme is not None:
+            self.theme = other.theme
         if self.is_capable(ItemCapabilities.HasBackgroundAudio):
             log.debug(self.background_audio)