add iimpi toolchain definition
enhance unit test for --list-toolchains
only list toolchain elements once in output of --list-toolchains (fixes #984)
fix remarks
Merge pull request #993 from boegel/iimpi_tc

add iimpi toolchain definition & fix --list--toolchains
prepend robot path with download location of files when --from-pr is used
fix broken unit test
Merge pull request #995 from boegel/from_pr_robot

prepend robot path with download location of files when --from-pr is used