unit test commented out for now.
sequential mode untested

printing will be done somewhere else

Additionally service 8 unit test added

validity buffer length is printed ti check whether it works
exception handling for setting up com if

in serial mode

commit b4795b4a
Author: Robin.Mueller <robin.mueller.m@gmail.com>
Date:   Thu Jan 2 21:24:24 2020 +0100

    listener mode notification print

commit db2c26db
Author: Robin.Mueller <robin.mueller.m@gmail.com>
Date:   Thu Jan 2 00:05:37 2020 +0100

    tmtc adapted for serial send and receive

commit faf01c5a
Author: Robin.Mueller <robin.mueller.m@gmail.com>
Date:   Mon Dec 30 20:55:36 2019 +0100

    service 3 testing first custom definition added

commit b8052826
Author: Robin.Mueller <robin.mueller.m@gmail.com>
Date:   Mon Dec 30 20:21:22 2019 +0100

    tmtc refactoring, service 3 tm and tc handling continued

commit 2774a1c2
Author: Robin.Mueller <robin.mueller.m@gmail.com>
Date:   Mon Dec 30 01:12:54 2019 +0100

    hk service print init, hk service test plan added

commit 03596fa7
Author: Robin Mueller <robin.mueller.m@gmail.com>
Date:   Sun Dec 29 02:06:03 2019 +0100

    tmtc script service 3 init