Update git submodules

Update git submodules

* Update docs/submodules/appc.git from branch 'master'
  to a50f4bb4d854fb18eea62dd0601e52886e1c823e
  - Added Junit Class for ParamsHandlerActivator

    Added Junit Class for ParamsHandlerActivator

    Issue-ID: APPC-1372
    Change-Id: I1198cd62354e8781f4fe9e07676ad64fc7f3ccf9
    Signed-off-by: Sudarshan Kumar <sudars19@in.ibm.com>
  - upgrade databind artifact

    upgrade jackson's databind
    from 2.8.11.2 to 2.8.11.3

    Change-Id: I9bf3ab8021f91f6ed36bdffdacbaeeac78d2e87c
    Issue-ID: APPC-1533
    Signed-off-by: Taka Cho <takamune.cho@att.com>