Fix Alert Dialog title missing on some Android versions

Fixed issue #37 - the "Update Available" dialog title was not displaying on Android 6 & 7. Thanks @janicelco for reporting this and providing some examples.

Add greek translation

Adds

Add server control of version check

Add the ability for the server file to force or hide a version check display. See #26.

Improve dialog layouts for long translations

Button text was being truncated for some languages like French and Russian (#23). Fixed by @pirishd in #24. 🙌

Add Chinese support

Add strings for Chinese support (to correctly match the README)