[Fuego] fixes for the linaro and rt tests

Hi Tim

Please consider merging these patches.

[PATCH 1/4] linaro: localhost does not require ssh

This ones is self explanatory (no SSH if you use the local board)

[PATCH 2/4] linaro: update to python3

This one uses pip3 because the upstream python scripts are for
python3 now.

I thought about adding the dependencies to the Docker install
scripts, but since the requirements are in the upstream repository
I thought it is fine leaving them as they are (you can always
install them in advance and then skip this phase)

[PATCH 3/4] hackbench: fix the chart config file

I think this was some copy paste file, which is fixed now.

[PATCH 4/4] rt: search for the binary if the build phase is skipped

This are all very similar fixes where we enable support for
running binaries that already exist on the board's file system.
For example, because you install rt-tests via apt-get and then
you skipped the Fuego build phase.

Let me know what you think!

Thanks,
Daniel