HIVE-4266 - Refactor HCatalog code to org.apache.hive.hcatalog

[Eugene Koifman]

I'm planning to change the package name of all hcatalog classes
sometime this week (as was promised for 0.12).
This is likely to affect any outstanding hcatalog patches on trunk.
Please try to have them checked in as soon as possible.

Thanks,
Eugene