[R2.2 Release] Release 2.2 branch is created

[Liu, Ming (Ming)]

hi, all,

All major JIRAs targeted for R2.2 release already merged, so I created the R2.2 
branch today. And I asked Steve to help to setup auto regression test for this 
branch.
So we hope to release R2.2 within one month with several RC expected. So the 
target R2.2 release date will be early September.
Thanks all for contributing.

thanks,
Ming