fix remove/reinstall of config-file

A remove/reinstall of config-file failed like this:
[ERROR] global-config does not define the variable ocamlfind.
[ERROR] global-config does not define the variable ocamlfind.
add source depext to let aacplus pass CI
ackdo-reloaded: install into OPAM prefix, not /usr/local for system compiler
acpc: add depexts for aclocal
ackdo-reloaded: fix typo in opam
cairo2: dup ubuntu depexts from debian ones
Merge pull request #1960 from edwintorok/master

fix remove/reinstall of config-file
Merge pull request #1961 from raphael-proust/master

ocaml-acme: library for interacting with acme
meta-conv archive has changed upstream, so update it
fix cairo2 depext (dont install lablgtk2 externally)
Merge pull request #1962 from mirage/fix-aacplus

add source depext to let aacplus pass CI
Merge pull request #1965 from avsm/fix-acpc-depext

acpc: add depexts for aclocal
fix uri.1.6.0 syntax

opam-admin check was failing:
Fatal error: exception OpamSystem.Internal_error("File /home/edwin/something/opam-repository/packages/uri/uri.1.6.0/opam: Bad format! Expected a formula list of the form [ "item" {condition}... ], got option(ident(ounit),{symbol(<) string("1.0.2")})")
Merge pull request #1966 from mirage/fix-meta-conv-archive

meta-conv archive has changed upstream, so update it
Merge pull request #1964 from avsm/fix-ackdo-reloaded-system-install

Fix ackdo reloaded system install
Merge pull request #1963 from avsm/add-ubuntu-depexts-for-cairo2

cairo2: dup ubuntu depexts from debian ones
Merge pull request #1967 from edwintorok/master

fix uri.1.6.0 syntax
Convert lwt depopt constraint into a conflict

This ensures that the wrong version of react wont be picked up
when installing eliom
Merge pull request #1969 from avsm/fix-eliom-compile

Convert lwt depopt constraint into a conflict
Merge pull request #1968 from raphael-proust/master

merlin-acme