Add ipc_shutdown signal
Implement error handling in ipc_send_message
Add a convenience Con name property accessor
Fix overlinking with json-glib and gio

Move con_new to a private header. Move json-glib and gio to
Requires.private in the pkg-config. This removes these libraries from
the gir and typelib.
Add default prefix to configure
Add const qualifer to functions
Remove unused header includes
Bump to version 0.1.1