This changes the base yocto reference to the gnomeostree-3.14-dizzy
branch in gnome:gnome-continuous-yocto.

Additionally it does a few poky specific changes:
* Drop ca-certificates from manifest in favour of the one
  from poky. This fixes a directory name conflict when replacing
  the poky one with the ostree build one. And anywy, the poky one
  is probably better maintained.
* Change refereces from "tmp-eglibc" to "tmp-glibc" as this got
  directory got renamed in poky (due to switching to glibc).