use composer install if we detect composer

PLUS… support caching of ~/.composer !!!
opps, need to use sub.cmd
FIX ALL THE SPECS
use a fold
add some default args for composer
cleaner way of doing default for composer
self-update composer if there is a composer.json file
Merge pull request #276 from travis-ci/jk_composer_caching

Composer updates
Disable npm spinner
Merge pull request #277 from bendrucker/npm-spinner

Disable npm's spinner
Set python_version correctly for PyPy3

Fixes https://github.com/travis-ci/travis-ci/issues/2611