Added sensor and rules

Added sensor and rules

JIRA: PHAROS-318

Adds pharos.py which talks with the pharos dashboard to detect when bookings
are created and stores the needed information in the stackstorm datastore.
By default, the sensor will poll the dashboard every 30 seconds to check for changes.

The dashboard sensor will dispatch the triggers defined in dashboard_listener.yaml.

The rules in rules/* links the triggers thrown by the api sensor to workflows which will
do the work of deploying / cleaning the hosts.

Change-Id: I7411a16ebbb48739a8f1f5b924dea6493c400071
Signed-off-by: Parker Berberian <pberberian@iol.unh.edu>