new SQL function SINCE_EPOCH for VoltDB only, this can be an example for the following new SQL funtions
Merge pull request #560 from jxchinaren/eng4695

new SQL function SINCE_EPOCH for VoltDB only, this can be an example for...
Replace tabs with whitespaces following Volt's Coding Style
Reslove the type conversion error for Ubuntu and CentOS
Merge pull request #561 from VoltDB/ENG-4695

Eng 4695. Passed Jenkins.