slugbuilder: Bump buildpacks
slugbuilder: Bump buildpacks

https://github.com/cloudfoundry/staticfile-buildpack/compare/8f0d070e...5d6a67be
https://github.com/heroku/heroku-buildpack-ruby/compare/52b7238c...cdef996a
https://github.com/heroku/heroku-buildpack-nodejs/compare/8010e251...5f7dcf14
https://github.com/heroku/heroku-buildpack-python/compare/92b4f5e8...998f996a
https://github.com/heroku/heroku-buildpack-java/compare/ecbd6949...4296d60e
https://github.com/heroku/heroku-buildpack-scala/compare/01ef3f24...a7790893
https://github.com/heroku/heroku-buildpack-play/compare/2a783340...d94c86ad
https://github.com/heroku/heroku-buildpack-php/compare/2c8d01ff...cd2d1399
https://github.com/heroku/heroku-buildpack-go/compare/70eee647...91c7eeae

Signed-off-by: Jonathan Rudenberg <3692bfa45759a67d83aedf0045f6cb635a966abf@titanous.com>

flynn/flynn,lmars/flynn,lmars/flynn,lmars/flynn,philiplb/flynn,flynn/flynn,philiplb/flynn,philiplb/flynn,philiplb/flynn,philiplb/flynn,flynn/flynn,lmars/flynn,lmars/flynn,flynn/flynn,flynn/flynn