CDAP-451 Remove gateway related code
Update documentation
Remove passport related code
Addressing comments
Order config properties
(CDAP-381) Refactor MapReduce API to use Configurer style API.
Merge pull request #546 from caskdata/feature/unify-api

(CDAP-381) Refactor MapReduce API to use Configurer style API.
Merge pull request #542 from caskdata/feature/CDAP-451-DeprecateGateway

CDAP-451 Remove gateway related code
(CDAP-355) Insecurely pass userId from Router to downstream processes