[ta] Add TA verify and merge jobs

Includes:

    - TA-specific macros and templates to akraino_templates/

    - Verify and merge jobs for all the "ta/*" git repositories that
      produce RPMs. Merge jobs will upload RPMs to Nexus repository
      "images-snapshots".

    - Verify jobs for the three supporting tool and configuration git
      repositories ta/{manifest|build-tools|rpmbuilder}

    - Image build job to produce the TA end product: ISO image

    - Publish ISO images to Nexus

    - Moved shell scripts to jjb/shell

Signed-off-by: Saku Chydenius <saku.chydenius@nokia.com>
Change-Id: I2b1ecd6f34c2dd5f5c8fbb9ff09ab180d943a3d9