Bump version for new release

[bachdavi]

Bump version to 0.2.2 and update the CHANGELOG.md

[cpetitpas]

Version 0.2.2 seems fine....although load_model > load_models is a breaking change. Note that Pkg.add("RAI") does not update the version if already added. I did Pkg.update("RAI") and got the update to 0.2.2. I subsequently removed it via Pkg.rm("RAI") and then re-added it....and got version 0.2.2.