chore(package): update rollup-plugin-json to version 3.1.0

Closes #7

Author: greenkeeper[bot]

package.json

@@ -24,7 +24,7 @@
     "rollup-plugin-browsersync": "^0.2.6",
     "rollup-plugin-commonjs": "^9.1.0",
     "rollup-plugin-copy": "^0.2.3",
-    "rollup-plugin-json": "^2.3.0",
+    "rollup-plugin-json": "^3.1.0",
     "rollup-plugin-node-builtins": "^2.1.2",
     "rollup-plugin-node-globals": "^1.2.0",
     "rollup-plugin-node-resolve": "^3.3.0",