Version bump and CHANGELOG update after branching out for 7.2.0.
Bump ffi version to something compatible with chef.
Merge pull request #349 from opscode/sersut/ffi-bump

Bump ffi version to something compatible with chef.
Save IAM security credentials only if hint is present
Filter IAM from metadata unless 'iam' hint is present.
Merge pull request #350 from opscode/mcquin/chef-1558

Save IAM security credentials only if hint is present
add Object#to_json monkeypatches

because the JSON gem has infected the universe with them and I don't
have time to clean it all up right now.
Merge pull request #358 from opscode/lcg/add-json-compat

add Object#to_json monkeypatches