Remove Application and friends, because they are still not ready.

* gio/src/action.[hg|ccg]:
* gio/src/actiongroup..[hg|ccg]:
* gio/src/application.[hg|ccg]:
* gio/src/applicationcommandline..[hg|ccg]:
* gio/src/simpleaction..[hg|ccg]:
* gio/src/simpleactiongroup.[hg|ccg]: Removed.
* gio/src/filelist.am:
* goi/giomm.h: Do not mention them.
See bug #637445#c29