setup.sh - Adapt to local version of composer/bower/karma

setup.sh - Adapt to local version of composer/bower/karma

 * For developers who work with many builds, it's better to have one copy of
   bower/karma rather than reinstalling an extra 50mb for each build.
   If a system already has a copy of these, then don't forcibly download them.
   (If you really want extra copies, you can run "npm install" yourself.)
 * Documentation for composer is historically a bit inconsistent about
   whether to use "composer" or "composer.phar".  Work with either.