clean up libraries builds
fix ImageMagick download sources for older releases
no longer need to ignore Hammer 'builds' dirs
clean up exts
clean up main deps
make -j 9
use -bare for ext and ext name for merged
fix prefix and quoting
factor out ext install and allow pulling external ones
add new relic
use ext folder name
default to beta S3 for now
build mysql and pgsql exts statically
no longer bundle memcached ext
nicer errors, warnings and notices
allow index.php mode without composer.json
use COMPOSER_HOME, not just COMPOSER_CACHE_DIR, in preparation for future changes
support COMPOSER_GITHUB_OAUTH_TOKEN config var
inline notice for custom composer.phar should suffice
fix composer's version warnings to STDOUT instead of STDERR breaking things