s/worker-/hoodie-plugin-<pluginname>/ on `hoodie install <pluginname>`

* * *

This commit was sponsored by The Hoodie Firm.
You can hire The Hoodie Firm:
http://go.hood.ie/thehoodiefirm

* * *

This commit was sponsored by The Hoodie Firm.
You can hire The Hoodie Firm:
http://go.hood.ie/thehoodiefirm
[fix #38] adds graceful-fs module
write to package.json when installing a plugin
remove plugins from hoodie.plugins package.json property on hoodie uninstall command
WHITESPACE: fix indentation of packages.js module