Hide default bundler clean output
Fix LPXC deadlock issue 

ryandotsmith/lpxc#7
Merge pull request #174 from heroku/schneems/less-verbose-default-cache

Hide default bundler clean output
remove rake tasks that use vulcan

the buildpack uses [hammer](http://github.com/hone/hammer)
Merge pull request #192 from heroku/schneems/fix-lpxc

Fix LPXC deadlock issue
Merge pull request #193 from heroku/remove_vulcan

remove rake tasks that use vulcan
Merge remote-tracking branch 'heroku/master'