Revert "Update INSTALL file to reflect current state"

This reverts commit 5de20a33.

Wrong branch...

INSTALL

@@ -10,30 +10,23 @@ directory (e.g. /usr/include, /usr/lib/ocaml, or .).
 Dependencies:
 
   - oasis (only needed if there is no setup.ml, e.g. when building from git)
-  - ocamlfind
-  - ocamlgraph
+  - ocamlfind (package called ocaml-findlib)
+  - ocamlgraph (package ocaml-ocamlgraph)
   - readline
   - minisat (at least minisat 2)
-  - pgsolver
 
 On Debian or Ubuntu, install the following packages:
 
   - git
   - build-essential
+  - oasis
+  - libocamlgraph-ocaml-dev
+  - libreadline-dev
   - minisat
-  - opam
 
-And then execute the following:
-
-    opam config setup (# And follow the instructions)
-    opam install oasis ocamlfind ocamlgraph pgsolver
 
 Build
 -----
-Make sure your opam environment is loaded with:
-
-    eval `opam config env`
-
 In case there is no setup.ml yet, create it with oasis:
 
     oasis setup