Non-exit version of elisp-lint-files-batch

[psionic-k]

Small change request. I'm using an elisp file to run the lints, using --script rather than --batch to push more work into elisp and less bash / Makefile.

The printing in batch mode is appropriate to this style, but the unconditional exit behavior is not:

https://github.com/gonewest818/elisp-lint/blob/master/elisp-lint.el#L511

I want to change my configuration between invocation on the package lisp and the test lisp, specifically --no-package-lint on tests.

Can this get a switch to return the exit code instead of exiting on it?