Add count of tweets to config doc

[sjacks26]

We have a count of the number of tweets lost to stream limits in the collector config doc. Can we add a count of the number of tweets we collect?

[jhemsley]

IF we do this, we would want to add this to the inserter stage.
After a successful insert, we should add the number of tweets inserted to a value in mongo config.

[sjacks26]

Will probably go here: https://github.com/bitslabsyr/stack/blob/master/app/twitter/mongoBatchInsert.py