Adds support for Gitlab CI to run the scala tests

See merge request !14

Adds support for older kernel Versions < 4.8

See merge request !13

* assumption: control slave is first in address map; following a
  non-control slave / custom
* added function to compute number of slaves for a PE coordinate
* status core now checks number of slaves an increase slot ids acc.

* error in parser caused it to fail when run without options

* remove support for 2016.2, 2016.3

* XDC set to unmanaged to avoid problems
* /uArch/irq_0 and /InterruptControl/irq are now connected by default
* renamed constant zero properly

* XDC for system clock pin accidentally had ILA instance in it
* set '-unmanaged' flag to avoid the problem in the future

* related to #137

* related to #137, but does not seem to fix it completely

* hierarchical cells make it more difficult to find connected AXI ports
* creating a correct address map would sometimes fail when using nested
  hierachical cells, fixed now

  * must not be queried, if it is not enabled

  * intermediate hierarchical ports do not inherit CONFIG values or
    other properties from their sources
  * e.g., CONFIG.DATA_WIDTH is not set on master ports, preventing
    detection of the interface width
  * implemented new common method: tapasco::get_aximm_property
  * will travel down to original master(s) and report the value of the
    given property from there; will raise an error if multiple,
    differing values are found
  * used in axi4mm Architecture