It makes tests easiers and lighten the code in view.py

The code in the view is lighter, and the generic part could have been moved to utils

Doing so allows more grain control over the tests, as sup_process is just a
syntax sugar over RPC calls.

test / runner: new test for runSoftwareWithLock and runInstanceWithLock, which are both base functions of the webrunner

This also makes the function easier to test

  Now people can easily add tests

  slapos/builder was removed.

It's not needed anymore to create a user at first launch of webrunner. Credential can be created from slapos recipe directly.
Webrunner can also clone default repository at first launch.

/reviewed-on nexedi/slapos.toolbox!7

  Also don't interrupt of parse command output fails