Fix package.json repository URL

Author: thibaudcolas

package.json

@@ -23,7 +23,7 @@
   ],
   "repository": {
     "type": "git",
-    "url": "https://github.com/springload/draftail.git"
+    "url": "git+https://github.com/springload/draftail.git"
   },
   "bugs": {
     "url": "https://github.com/springload/draftail/issues"