Package android contains code specific to running the Perkeep client code as a child process on Android. This removes ugly API from the client package itself.
IsChild reports whether this process is running as an Android child process and should report its output in the form that the Android uploader app expects.
NoteFileUploaded is a hook for pk-put to report that a file was uploaded. TODO: move this to pkg/client/android probably.
StatusReceiver is a blobserver.StatReceiver wrapper that reports the full filename path and size of uploaded blobs. The android app wrapping pk-put watches stdout for this, for progress bars.