Make UpdateCheacker ready for Android Marshmallow

[Frederik Götz]

Hi,

with Android Marshmallow the apache http client is no longer supported and only works with a workaround. See Documentation:
https://developer.android.com/preview/behavior-changes.html#behavior-apache-http-client

Can you please change to HttpURLConnection? Or OkHttp?

Thank you :)

[Anant Shah]

Not working in Marshmallow