All executor feature.

Proposing a small feature that will dynamically set weight to the number of executors. Example: I wanted to be able to use a templated build job that can run on any node, with any number of executors. When this particular job builds it can be on the only thing building as it does cleanup that would cause any other build to fail. This plug in worked great, until I had nodes with different number of executors. Take a look, let me know if anything needs correcting.