adding locust files for testing

[sstults]

This is a locust load test file that reproduces the ES registry calls. There's also a function to generate random bounding box heatmaps.

[coveralls]

Coverage remained the same at 99.46% when pulling 2af4412706d9eb214add6f7fa39f008f489bbd3a on sstults:locust into bcf142565d645aabc298b2337efad54d2c6da406 on boundlessgeo:master.