java/syncbase: Add Cloud support in Android HLAPI

Init now uses an Options Builder that allow you to go the cloud-
supported route or the offline route.

This also carries through the logLevel changes from v.io/c/23754

Also
- removes sUserdataCollection in favor of accessing it via
sDatabase.
- Calls the loginCallback.onSuccess() via executor.
- Adds the proxy flag (-v23.proxy=proxy) to allow devices to
  communicate across networks and with the cloud.

MultiPart: 2/2
Change-Id: I26f3ac17fcfe0597b92b8c9cb427e17bc15cf272
20 files changed