Feature: allow saltStep.returnHandlers config files to be reloaded dynamically

[gaetanquentin]

Would it be possible to reloadsaltStep.returnHandlers config files dynamically.

For now we have to stop/start rundeck, it is very time expansive.

Exemple: saltStep.returnHandlers=/data/rundeck/server/config/saltstep_return_handlers.yaml

each time i modify saltstep_return_handlers.yaml content i have to restart rundeck