[FIXED JENKINS-23117] Supported launcher in Perform Buildstep.
[JENKINS-23117] Added help tests for createLauncher.
[JENKINS-23117] Add tests for launcher. And found and fix that a build does not fail even when a builder in timeout action throws an exception.
[JENkINS-23117] Support BuildWrapper#decorateLauncher.
Merge pull request #30 from ikedam/feature/JENKINS-23117_SuppporLauncherInPerformBuildstep

[JENKINS-23117] supppor launcher in perform buildstep