cloudml_train() / jobs.R assumes scripts reside within the project directory

[missaugustina]

This uses getwd() to get the project's path to find the "entrypoint" file (which could be problematic). When trying to run a script that's not in the project, specifying a relative path is really fragile. Docs don't indicate this limitation. A flag/option to support fully qualified paths would nice.

https://github.com/rstudio/cloudml/blob/master/R/jobs.R#L64

I guess the current workaround is to write a script in your local project that points to the one you want. But this should still be clarified & documented.