Adds a post commit hook to notify devs of acceptance tests relating to their last commit

Now that we have `common/automation/webdriver/static_files/knows_out.yml`,
it doesn't hurt to simply notify devs of the impact their code changes.
this parses the yaml file each time for every file - can we instead parse the yaml file once, and output all relevant tests? It will cut down on duplicate tests in the list, as well as be faster.