Add pulseaudio GStreamer element from gst-pulse. Development will continue here instead of pulseaudio SVN. Fixes bug ...

Original commit message from CVS:
* configure.ac:
* ext/pulse/Makefile.am:
* ext/pulse/plugin.c: (plugin_init):
* ext/pulse/pulsemixer.c: (gst_pulsemixer_interface_supported),
(gst_pulsemixer_implements_interface_init),
(gst_pulsemixer_init_interfaces), (gst_pulsemixer_base_init),
(gst_pulsemixer_class_init), (gst_pulsemixer_init),
(gst_pulsemixer_finalize), (gst_pulsemixer_set_property),
(gst_pulsemixer_get_property), (gst_pulsemixer_change_state):
* ext/pulse/pulsemixer.h:
* ext/pulse/pulsemixerctrl.c:
(gst_pulsemixer_ctrl_context_state_cb),
(gst_pulsemixer_ctrl_sink_info_cb),
(gst_pulsemixer_ctrl_source_info_cb),
(gst_pulsemixer_ctrl_subscribe_cb),
(gst_pulsemixer_ctrl_success_cb), (gst_pulsemixer_ctrl_open),
(gst_pulsemixer_ctrl_close), (gst_pulsemixer_ctrl_new),
(gst_pulsemixer_ctrl_free), (gst_pulsemixer_ctrl_list_tracks),
(gst_pulsemixer_ctrl_timeout_event), (restart_time_event),...