CDAP-633 RunId of Currently Running Program 

Based on the discussion at
https://issues.cask.co/browse/CDAP-633

history endpoint is moved to /runs endpoint, with default call to runs will return all currently active and past runs of a program.

while /runs?status={completed/failed/active} can be used to filter the returned records.

This PR contains CLI command change and UI changes as well.
This can be merged with the one in line 788, isn't it? Simply have

`ProgramRunStatus runStatus = (status == null) ? ProgramRunStatus.ALL : ProgramRunStatus.valueOf(status.toUpperCase());`