Support for multiple simperiumClients in Android

[bayareacoder]

Current Android library does not seem to support multiple Simperium clients in an app since the SQLite database is hardcoded in com.simperium.android class AndroidClient:
this.mDatabase = this.mContext.openOrCreateDatabase("simperium-store", 0, (CursorFactory)null);
Multiple client supports works in IOS library since multiple managed object contexts are used via the CoreData framework.
Multiple clients is sometimes required to implement specific functionality.
Requesting to implement support for this.

[beaucollins]

With a custom implementation of ClientFactory you should be able to use the Simperium constructor with a factory that opens any database you choose.

I'll take a closer look at making it easier to customize the provided AndroidClient.