Check retcode return value of the highstate
Check retcode return value of the highstate

Not only the `success` field indicates a successfull highstate
execution, but also the `retcode` field being 0 as a result of the
execution.

kubic-project/velum,vitoravelino/velum,vitoravelino/velum,ereslibre/velum,irfanhabib/velum,MaximilianMeister/velum,MaximilianMeister/velum,kubic-project/velum,MaximilianMeister/velum,ereslibre/velum,irfanhabib/velum,kubic-project/velum,ereslibre/velum,vitoravelino/velum,irfanhabib/velum,MaximilianMeister/velum,vitoravelino/velum,ereslibre/velum,kubic-project/velum,irfanhabib/velum