Update AFNetworking (to 2.4.1), GRMustache (to 7.3.0), MRProgress (to 0.7.0), WebViewJavascriptBridge (to 4.1.4).

Bunch of people experiencing network issues, and the changelog for AFNetworking didn't suggest any breaking changes. GRMustache and WebViewJavascriptBridge were also out-of-date and changelogs didn't look bothersome. MRProgress learned a bunch of new, possibly helpful things, and has some handy fixes too.