For ENG-5201, add caching for reverse DNS and localhost lookups
For ENG-5201, remove erroneous reverse DNS lookup
For ENG-5201, patch up license check
For ENG-5201, remove uneccessary memoization and handle failed local address lookup
For ENG-5201, fix timeout and comment based on Ning's feedback
Merge pull request #797 from VoltDB/ENG-5201

Eng 5201 Add reverse DNS cache and commit hooks to prevent uncached reverse lookups