Update package.json

Revised license information to provide a SPDX 2.0 license identifier according to npm v2.1 guidelines on license metadata - see also https://github.com/npm/npm/releases/tag/v2.10.0

Author: mwittig

package.json

@@ -8,12 +8,7 @@
   },
   "main": "src/index",
   "homepage": "https://github.com/mwittig/node-milight-promise",
-  "licenses": [
-    {
-      "type": "MIT",
-      "url": "https://github.com/mwittig/node-milight/blob/master/LICENSE"
-    }
-  ],
+  "license": "MIT",
   "repository": {
     "type": "git",
     "url": "https://github.com/mwittig/node-milight-promise"