Add support for release ready directory structure.

This commit introduces support for running tests from apps/
applications. Specifically, any file matching '*_test.erl' under apps/ or
top-level test/ will now be considered a test_file, per bin/etest-runner. The
runner invocation has been made to include apps/*/ebin on the code path, as
well.

These changes have been made to support a common multi-application directory
structure.

Signed-off-by: Brian L. Troutwine <brian@troutwine.us>
Merge pull request #4 from blt/apps_dir_support

Add support for release ready directory structure.
explain how to pass erl params to etest-runner
Merge pull request #7 from phuesler/master

Documentation: How to pass args to erl command