Fix argument order for s-ends-with?

See bbatsov/prelude#253
Merge branch 'master' into unit-tests

* master:
  Fix argument order for s-ends-with?
Fix unit test

We should really test the checker, and not merely Emacs properties.
Add that Emacs Lisp does not check during package installation

Regression tests for #45 and bbatsov/prelude#253