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