1. create a 011 dir in each HCat submodule to hold these classes
2. update build to place these classes into jars
3. figure out how to test this
The goal is for users who were using public API (e.g. HCatLoader) in their programs to be able to upgrade to hive 0.12 and have their programs still work without change.
The compatibility layer will have a sunset clause to be removed in 2 releases.