Metrics collection

This script will collect a DC's total desired and actual when run. 

**TODO**:
- [ ] Collect pending also
- [ ] Tests
- [ ] Dump the data to Cloud metrics
Hmm... in that case would it make sense for another function to do more filtering later on?  Since this function will split stuff up by group ID, and filters out those without group IDs, something else can then divide up the results in whatever way it likes?