Create tool to convert the measurements to a format the BWAuths can use

[DonnchaC]

The TorFlow bandwidth scanner includes an aggregate.py script which takes measurement data and creates the bandwidth file that the bandwidth auths use for calculating their votes. The aggregation scripts depends on the dead Tor controller library TorCtl.

I have updated the aggregate.py script to use the Stem Tor controller library instead. This torflow branch is at https://github.com/DonnchaC/torflow/compare/remove-torctl-dependency.

[DonnchaC]

The aggregate.py code mentioned above is included in the repo at https://github.com/TheTorProject/bwscanner/blob/develop/scripts/aggregate.py. It needs to be tested to ensure the aggregated files are the same format as the existing torflow generated files.