Prepare release v2.1.2

Author: jsor

package.json

@@ -7,7 +7,7 @@
     "email": "jan.sorgalla@dotsunited.de",
     "url": "https://dotsunited.de"
   },
-  "version": "2.1.1",
+  "version": "2.1.2",
   "repository": {
     "type": "git",
     "url": "https://github.com/dotsunited/sliding-navigation.git"