[Linaro-validation] ARMHF test ARMEL master

Hi.

I've just realized that we'll likely see issues when test images start showing up as armhf. Our master image compiler that builds a few of the tests is going to target armel.

I'd like to propose that we re-purpose the master image. I'd like to _stop_ using it for building software. That is: all lava-test install steps will be invoked in the _test_ image.

We can apply this without requesting our users to rewrite their test scenario definitions. I'd like to propose rewriting the scenario file to invoke any lava-test-install _after_ the boot test image step.

Thanks ZK