2.2.0

CHANGES:

• lib: use ocaml5-compatible macros
• use ounit2

CRC

• Port to jbuilder @kc284
• Drop xen support (no longer needed now that mirage uses the new ocaml-git) @kc284

Declare this package stable

Merge pull request #24 from johnelse/build-deps

Add ocamlbuild and ocamlfind to build deps

Minor improvements

• simplify unit tests
• build docs
• improve travis integration