Run mocha without --parallel

Invoking mocha without --parallel in test-unit-cov works well in other
projects, but causes the pretest-unit/posttest-unit scripts not to be
run.  Rather than duplicating these (or adding forwarding scripts),
minimize duplication by removing --parallel in test-unit.

Signed-off-by: Kevin Locke <kevin@kevinlocke.name>

Author: kevinoid

package.json

@@ -47,10 +47,10 @@
     "test": "npm run lint && npm run test-unit",
     "test-cov": "npm run lint && npm run test-unit-cov",
     "pretest-unit": "node test-bin/set-up-test-repos.js",
-    "test-unit": "node --throw-deprecation --unhandled-rejections=strict node_modules/mocha/bin/mocha --parallel --require ./test-lib/root-hooks.js --recursive test",
-    "posttest-unit": "rimraf test-repos",
     "//": "Note: nyc incompatible with --parallel.  See https://github.com/istanbuljs/nyc/issues/1328 and https://github.com/mochajs/mocha/issues/4372",
-    "test-unit-cov": "nyc --reporter=lcov --reporter=text node --throw-deprecation --unhandled-rejections=strict node_modules/mocha/bin/mocha --require ./test-lib/root-hooks.js --recursive test",
+    "test-unit": "node --throw-deprecation --unhandled-rejections=strict node_modules/mocha/bin/mocha --require ./test-lib/root-hooks.js --recursive test",
+    "posttest-unit": "rimraf test-repos",
+    "test-unit-cov": "nyc --reporter=lcov --reporter=text npm run test-unit",
     "upload-cov": "codecov < ./coverage/lcov.info && coveralls < ./coverage/lcov.info",
     "version": "npm run changelog && echo && echo === Please edit CHANGELOG.md as desired, then exit === && echo && $npm_config_shell && git commit -m \"Update CHANGELOG.md for $npm_package_version\" CHANGELOG.md",
     "version-deps": "npm install conventional-changelog-cli david depcheck git-branch-is hub-ci-status"