* updated to scalatest 3.0.5
* use scalatest runner instead of junit
Output is far more readable, and makes console (incl. travis) reports
actually usable.
Turned off test logs as error reporting is enough to figure out what
happens.
The only downside is that we can't use junit's categories to group
tests, like we did for docker related tests. We could use nested suites,
but that seems to be overkill so I just removed the categories. Users
will only have the possibility to either skip/run all tests.
* update scala-maven-plugin to 3.4.2
NB: This requires maven 3.5.4, which means that we currently need to
manually install maven on travis.
Also updated Docker java version to 8u181 (8u171 for compiling).
This is a regression caused by 0794fb8d5a,
because default values provided for `git.commit.id` `git.commit.id.abbrev`
are not overriden by git-commit-id-plugin plugin.
Instead we specify these variables when doing the docker build.
Dependency to `git` has been removed, we now use `notag` when building without
a git directory.
In order to reliably fetch all dependencies, we do a first blank build
(with no source files), then we copy the sources and do a real commit.
This is a simpler and more robust approach.
Also, fixed the .dockerignore to filter out IDE files.
