feat(package): Intergate Rollup for ES6 transpilation

package.json

@@ -4,7 +4,7 @@
   "description": "Display a calendar for date selection or for planning management, in different colors and sizes",
   "main": "dist/bulma-calendar.sass",
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "build": "gulp"
   },
   "repository": {
     "type": "git",
@@ -22,28 +22,30 @@
     "url": "https://github.com/Wikiki/bulma-calendar/issues"
   },
   "homepage": "https://github.com/Wikiki/bulma-calendar#readme",
-  "scripts": {
-    "build": "gulp"
-  },
   "devDependencies": {
     "@babel/core": "^7.0.0-beta.39",
     "@babel/preset-env": "^7.0.0-beta.39",
     "babel-core": "^7.0.0-beta.3",
     "bulma": "^0.6.2",
+    "camelcase": "^4.1.0",
     "conventional-github-releaser": "^2.0.0",
     "del": "^3.0.0",
     "gulp": "^3.9.1",
     "gulp-autoprefixer": "^4.1.0",
     "gulp-babel": "^7.0.1",
+    "gulp-babel-minify": "^0.3.0",
+    "gulp-better-rollup": "^3.0.0",
     "gulp-bump": "^3.1.0",
     "gulp-clean-css": "^3.9.2",
     "gulp-concat": "^2.6.1",
     "gulp-conventional-changelog": "^1.1.11",
     "gulp-git": "^2.5.1",
     "gulp-postcss": "^7.0.1",
     "gulp-sass": "^3.1.0",
+    "gulp-sourcemaps": "^2.6.4",
     "gulp-uglify": "^3.0.0",
     "gulp-util": "^3.0.8",
+    "rollup-plugin-babel": "^3.0.3",
     "run-sequence": "^2.2.1"
   },
   "files": [
@@ -53,5 +55,8 @@
     "dist/bulma-calendar.min.js",
     "LICENSE",
     "README.md"
-  ]
+  ],
+  "dependencies": {
+    "camelcase": "^4.1.0"
+  }
 }