SQOOP-1671: Fix incorrect merge from SQOOP-1645

(Veena Basavaraj via Jarek Jarcec Cecho)
SQOOP-1665: Sqoop2: Misc Cleanup / rename lingering connection to link

(Veena Basavaraj via Jarek Jarcec Cecho)
SQOOP-1673: DOC: Update Upgrade.rst to reflect the latest in the code

(Veena Basavaraj via Jarek Jarcec Cecho)
SQOOP-1510: Sqoop2: Refactor JobRequestHandler for submit/abort job and SubmissionHandler for get operation only

(Veena Basavaraj via Abraham Elmahrek)
SQOOP-1668: Update existing job meets NPE

(Qian Xu via Jarek Jarcec Cecho)
SQOOP-1675: Sqoop2: Update Upgrade.rst to to address Rb comments

(Veena Basavaraj via Abraham Elmahrek)
SQOOP-1676: Sqoop2: clientAPI.rst changes to reflect latest code

(Veena Basavaraj via Abraham Elmahrek)