feat(coverage): #61 - WIP - Generate contract testing coverage reports for both consumers and providers

Atm this collects coverage when enabled with '--coverage'. The coverage is collected with a granularity of spec response. I.e. spec.operations[x].responses[y] -> [interactionA, interactionB]

There's a dummy console reporter at the moment (lib/swagger-mock-validator/coverage/console-coverage-reporter.ts)

Pending:

• Create a proper reporter. File based? format?

• Should the user be able to set the path of the destination file

• e2e test (once the final reporter is implemented)

• Can be the coverage be mapped to a particular format so that HTML can be generated with other tool (e.g. https://github.com/gotwarlost/istanbul/blob/master/coverage.json.md)

• Fix the build. Looks like it didn't like my commit message