Set google analytics as empty value to do not throw error in UI console (#680)

Author: milanmajchrak

dspace/config/clarin-dspace.cfg

@@ -169,7 +169,7 @@ statistics.cache-server.uri = http://cache-server.none
 # citace.pro.allowed = true
 
 #google config
-# google.analytics.key =
+google.analytics.key =
 
 # The max number of events held in the GA buffer (default: 256)
 # google.analytics.buffer.limit = 256