shell: Make the application a GtkApplication subclass

This promotes better encapsulation and allows us to move
application logic out of main() and rename the confusingly
named control-center.c to main.c

https://bugzilla.gnome.org/show_bug.cgi?id=692174

shell/cc-application.h

@@ -0,0 +1,70 @@
+/*
+ * Copyright © 2013 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+#ifndef CC_APPLICATION_H
+#define CC_APPLICATION_H
+
+#include <gtk/gtk.h>
+
+G_BEGIN_DECLS
+
+#define CC_TYPE_APPLICATION (cc_application_get_type ())
+
+#define CC_APPLICATION(obj) \
+  (G_TYPE_CHECK_INSTANCE_CAST ((obj), \
+   CC_TYPE_APPLICATION, CcApplication))
+
+#define CC_APPLICATION_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_CAST ((klass), \
+   CC_TYPE_APPLICATION, CcApplicationClass))
+
+#define CC_IS_APPLICATION(obj) \
+  (G_TYPE_CHECK_INSTANCE_TYPE ((obj), \
+   CC_TYPE_APPLICATION))
+
+#define CC_IS_APPLICATION_CLASS(klass) \
+  (G_TYPE_CHECK_CLASS_TYPE ((klass), \
+   CC_TYPE_APPLICATION))
+
+#define CC_APPLICATION_GET_CLASS(obj) \
+  (G_TYPE_INSTANCE_GET_CLASS ((obj), \
+   CC_TYPE_APPLICATION, CcApplicationClass))
+
+typedef struct _CcApplication        CcApplication;
+typedef struct _CcApplicationClass   CcApplicationClass;
+typedef struct _CcApplicationPrivate CcApplicationPrivate;
+
+struct _CcApplication
+{
+  GtkApplication parent_instance;
+  CcApplicationPrivate *priv;
+};
+
+struct _CcApplicationClass
+{
+  GtkApplicationClass parent_class;
+};
+
+GType                  cc_application_get_type               (void) G_GNUC_CONST;
+
+GtkApplication        *cc_application_new                    (void);
+
+G_END_DECLS
+
+#endif /* CC_APPLICATION_H */