Combine all test runs for coverage

[Andrew Williams]

[Andrew Williams]

Code slug to use ... from istanbuljs/nyc#681

"test-mocha": "node ./bin/nyc --no-clean --silent --temp-directory=./.self_coverage mocha ./test/nyc.js ./test/process-args.js",
"report": "node ./bin/nyc --temp-directory ./.self_coverage/ -r text -r lcov report",