Gracefully Handle missing or not up-to-date Google Play Services Version

[joshjhargreaves]

As mentioned in TODO in the ReadMe, gracefully handing missing or not up-to-date version of Google Play Services desirable. Testing on devices where this is the case, exceptions are thrown when calling CastContext.getSharedInstance.

A rough solution approach might be to not show the cast button in cases where Google Play Services is not up-to-date or available, so something like this: https://github.com/joshyhargreaves/react-native-google-cast/pull/1/files. It might be necessary to handle cases where calls to the native Google Cast module, guard against these exceptions also also.

Any other ideas?