Removing panics on config and license loading errors. Nice error messages instead. (#2829)

i18n/en.json

@@ -2019,6 +2019,10 @@
     "id": "mattermost.config_file",
     "translation": "Loaded config file from %v"
   },
+  {
+    "id": "mattermost.unable_to_load_config",
+    "translation": "Unable to load mattermost configuration file:"
+  },
   {
     "id": "mattermost.current_version",
     "translation": "Current version is %v (%v/%v/%v)"