HardwareObjects submodule

Created by: mguijarr

At the moment the HardwareObjects submodule points to commit 96cae8 of the HardwareObjects repository. This commit is from the master branch of MXCuBE 2. I think we should not build MXCuBE 3 on top of the master branch versions of Hardware Objects, since it is unstable and some changes may be untested. In particular, I wanted to test latest MXCuBE 3 in "real situation" yesterday but I couldn't because the signature of a function changed in MiniDiff.py in master branch compared to 2.1. My question is : would you agree to use 2.1 versions of Hardware Objects as our HardwareObjects submodule ? If you are ok I can make a pull request for this, yesterday evening I created a 2.1 branch in the HardwareObjects repository.