CBQE-0: rename store_report func in plotter.py

to exclude confusing with store_report module

Change-Id: I63a1ca199bf3084673dc6e49e927ed294647523b
Reviewed-on: http://review.couchbase.org/28294
Reviewed-by: Andrei Baranouski <andrei.baranouski@gmail.com>
Tested-by: Andrei Baranouski <andrei.baranouski@gmail.com>