Add a test runner and tool for making implementation reports

Tets runner is based on earlier work by Ms2ger
fixup! Add a test runner and tool for making implementation reports
fixup! Add a test runner and tool for making implementation reports
fixup! Add a test runner and tool for making implementation reports
fixup! Add a test runner and tool for making implementation reports
fixup! Add a test runner and tool for making implementation reports
Merge pull request #495 from w3c/jgraham/runner

Add a test runner and tool for making implementation reports