Add initial infrastructure to run tests against an Asterisk process.
An not-yet-finished draft test doing registration is submitted to
validate communication towards Asterisk works.
The testsuite will be improved in follow-up commits, but this way other
people can already start using it and we can set up the dockerized setup
+ jenkins jobs to run it nightly.
Related: SYS#6782
Change-Id: I66f776d5df6fb5dc488d9e589b84a6b2385406e8
