This PR addresses minor issues with PS-package docker tests.
Historically rpm package version string was different from other packages, however, this is no longer the case, so updating tests to account for that (to simplify things - removing RPM-version parameter from dockerfiles because it is no longer used).
Configs that use 'linux-x64.tar.gz' (currently only "opensuse42.2") are failing, so fixing that in the script.
This automation is used for basic validation of PS packages during a release;
Covered configs:
ubuntu14.04
ubuntu16.04
ubuntu17.04
debian.8
debian.9
centos7
fedora25
fedora26
kalilinux
opensuse42.2
During the process Docker files are filled out and executed with Docker build;
During the build PS packages are downloaded onto Docker containers, installed and selected Pester tests from PowerShell Github repo are executed.
