Preserve ENV vars CPATH and CPPPATH (composable buildpacks)
update 'no version specified' devcenter url
Merge pull request #30 from davidjrice/preserve-env-vars

Preserve ENV vars CPATH and CPPPATH (composable buildpacks)
improve documentation in README
add a readme section for hackers
DRY up the hacking docs
ignore .DS_Store
use npm 1.3.x by default
Simple caching of node_modules across compiles