CBIDXT-117: Configurable datapath program.

accepts parameters via command line.

Change-Id: I8d2c0b5ab0ab8c3865e800dfb222742177fdc4b8
Reviewed-on: http://review.couchbase.org/39872
Reviewed-by: John Liang <johliang00@gmail.com>
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>