Bump exo version

Should have done this when introduced the use of
exo_gtk_dialog_get_action_area.

configure.ac.in

@@ -145,7 +145,7 @@ GTK_DOC_CHECK([1.9])
 dnl ***********************************
 dnl *** Check for required packages ***
 dnl ***********************************
-XDT_CHECK_PACKAGE([EXO], [exo-2], [0.10.0])
+XDT_CHECK_PACKAGE([EXO], [exo-2], [0.11.4])
 XDT_CHECK_PACKAGE([GLIB], [glib-2.0], [2.30.0])
 XDT_CHECK_PACKAGE([GIO], [gio-2.0], [2.30.0])
 XDT_CHECK_PACKAGE([GTHREAD], [gthread-2.0], [2.30.0])