chore: add missing typescript dependency, add package-lock.json

I suspect that the current problems with
saucelabs are due to a change transitive
dependency, but I'm not sure. I'm not
adding the package-lock.json to ensure
that this does not happen in the future.

package.json

@@ -56,6 +56,7 @@
     "mock-stdin": "^0.3.0",
     "mustache": "^2.1.3",
     "semver": "^5.0.1",
+    "typescript": "^3.4.3",
     "underscore": "^1.5.1",
     "webpack": "^1.12.6",
     "webpack-dev-server": "^1.12.1"