Update logging to use new shared logging style

In order to make it easy for logstash to pull and parse the logs we have
moved to a unified style of logging setup in backdrop-collector. This
commit pins the version of backdrop-collector to the latest and runs the
setup code.
Switching to latest version of backdrop-collector

The latest version of backdrop-collector has an extra parameter in set_up_logging() which allows one to specify the logfile_path. Previously logfiles were being created in a place relative to cron's working directory.
PEP8
Merge pull request #10 from alphagov/update-logging

Update logging
Merge branch 'update-logging' of github.com:alphagov/backdrop-pingdom-collector into update-logging

Conflicts:
	collect.py