Store sensor data in one collection per sensor

[jkubNTIA]

As per my discussion with Ranga, it would be nice to store sensor data in one collection per sensor rather than all sensor data in one big collection. This would have the following benefits:

1. As data sets get large, it is much easier and faster to select or delete data from a sensor if you only have to look at one data collection for the sensor.
2. We might eliminate issues like 140, 141, etc. that I had when we purge data and somehow mongodb is leaving around artefacts, like index values.

[ranganathanm]

http://docs.mongodb.org/manual/reference/method/db.createCollection/

Will do the trick.

[ranganathanm]

Neet to also think about schrading and how to distribute the data over a cluster as the db grows....

[ranganathanm]

f161878..3614ee5

Please delete your db and rebuild it using populate_db.py