The proxy must ensure that enable/disable calls are not reordered when
proxied; this change adds synchronization to prevent such reordering
that could happen following an onServiceConnected() callback, and to
ensure cross-thread visibility of writes.
Also, when the package is updated, the old service instance must be
unbound and the new one bound. This changes uses a separate
Connection object per service instance (package version) to avoid
confusing the binder objects.
Change-Id: I0907f7eed211b97ccfffa395754f1eb8ea8d8fec
