Add functionality specific for STACKS collectors

[sjacks26]

Add checks to see if STACKS collectors are actively collecting data.
Do this by going into the raw data dir and seeing if there is a file ending in 'tweets_out.json' for each collector that was created in the previous hour.

Add a nested object to config.py for STACKS specific parameters. Parameters should include path to STACKS directory, project names, and collector names for each project.

[sjacks26]

Implementation of this on houston runs into a problem if ServerReport runs at the very top of an hour. Need to have the code wait 1 minute if now.minute == 0.

[sjacks26]

A better long-term solution is to go into the appropriate log file and look for HTTP error code.

[sjacks26]

If not implementing the better long-term solution, need to at least add a longer delay. Right now, if ServerReport runs at minute < 5, it is pretty common that it doesn't find an expected raw data file and it throws a critical error.