Fixed asset rich query or range query workloads implementation do not work with big numbers of assets

[fraVlaca]

The issue was partly solved in #189 , however, I had to reduce the size of the total asset created to avoid timeout.
It seems that with a considerable number of created assets couch DB takes exponentially more time to complete the query; it does eventually complete it successfully but only after a long time and the time out of the tx.
You can find more info on the issue linked above