Add automatic versioning

Author: wojtekmaj

package.json

@@ -11,10 +11,14 @@
     "build-styles": "lessc ./src/DatePicker.less ./src/DatePicker.css",
     "copy-styles": "node ./copy-styles.js",
     "prepublishOnly": "npm run build",
+    "preversion": "npm run version-sample && npm run version-test",
     "test": "npm run test-eslint && npm run test-jest",
     "test-eslint": "eslint ./src",
     "test-jest": "jest",
-    "test-jest-coverage": "jest --coverage"
+    "test-jest-coverage": "jest --coverage",
+    "version": "npm run build && git add .",
+    "version-sample": "cd sample && npm version patch",
+    "version-test": "cd test && npm version patch"
   },
   "jest": {
     "setupFiles": [