allow to filter subgrap query to include only token
allow to only fetch token when doing a subgraph query

This is quite useful for exporters that are only displaying token and don't need the large overhead of other nodes.
display number of already exported items
do not join on metadata in matrix query if no metadata was requested
do not throw exception of no metadata was set
making the EventBus transient in order to avoid error messages on restarting tomcat
limit maximal step size
Merge branch 'exportspeed'