Moved calls to "RequestLibrary.<action> Request" in csit/suites/ (3)

Moved calls to "RequestLibrary.<action> Request" in csit/suites/ (3)

+ RequestsLibrary.Get Request
+ RequestsLibrary.Delete Request
+ RequestsLibrary.Put Request
+ RequestsLibrary.Post Request

Updated RequestLibrary calls in following directories

  csit/suites/sdninterfaceapp/
  csit/suites/sxp/
  csit/suites/topoprocessing/
  csit/suites/ttp/
  csit/suites/unimgr/
  csit/suites/usc/ (Removed due to failure)
  csit/suites/usecplugin/

Change-Id: I81a8f366835d31a3d70ea52bd99d8afd345aba1b
Signed-off-by: Junaid Zulfiqar <junaid.rao21@gmail.com>