build(app): install Commitizen locally

https://github.com/commitizen/cz-cli#optional-install-and-run-commitizen-locally

Author: stephlm2dev

package.json

@@ -28,6 +28,8 @@
     "@types/mocha": "5",
     "@types/node": "9",
     "chai": "4",
+    "commitizen": "^4.0.3",
+    "cz-conventional-changelog": "^3.0.2",
     "globby": "8",
     "mocha": "5",
     "nyc": "11",
@@ -63,7 +65,13 @@
     "posttest": "tsc -p test --noEmit && tslint -p test -t stylish",
     "prepack": "rm -rf lib && tsc && oclif-dev manifest && oclif-dev readme",
     "test": "nyc mocha --forbid-only \"test/**/*.test.ts\"",
-    "version": "oclif-dev readme && git add README.md"
+    "version": "oclif-dev readme && git add README.md",
+    "commit": "git-cz"
   },
-  "types": "lib/index.d.ts"
+  "types": "lib/index.d.ts",
+  "config": {
+    "commitizen": {
+      "path": "./node_modules/cz-conventional-changelog"
+    }
+  }
 }