- Remove pending call locking todo item
- dbus_connection_open now holds hard ref.  Remove todo item
- do proper locking on _dbus_bus_check_connection_and_unref
  and handle DBUS_BUS_STARTER. Remove todo item
- Warn on closing of a shared connection.  Remove todo item

* bus/bus.c, bus/connection.c, bus/dispatch.c, dbus/dbus-bus.c,
  dbus/dbus-connection.c: Use the dbus_connection_close_internal
  so we don't get the warning when closing shared connections

* test/test-service.c, test/test-shell-service.c: Applications
  don't close shared connections themselves so we unref instead of
  close

* test/test-utils.c (test_connection_shutdown): Close the connection

* dbus/dbus-bus.c (_dbus_bus_check_connection_and_unref): Changed to
  _dbus_bus_check_connection_and_unref_unlocked since we only call this
  method on a locked connection.
  Make sure we call _dbus_connection_unref_unlocked instead of
  dbus_connection_unref also.
  Handle DBUS_BUS_STARTER correctly

* dbus/dbus-connection.c (connection_record_shared_unlocked):
  Mark as shared and hard ref the connection
  (connection_forget_shared_unlocked): Remove the hard ref from the
  connection
  (_dbus_connection_close_internal_and_unlock):  New internal function
  which takes a locked connection and unlocks it after closing it
  (_dbus_connection_close_internal): New internal function which acts
  like the origonal dbus_connection_close method by grabbing a connection
  lock and calling _dbus_connection_close_internal_and_unlock
  (dbus_connection_close): Public close method, warns when the app
  trys to close a shared connection