Finish re-implementing 'make_clean_name'

[FrenjaminBanklin]

Currently the Widget class has a 'make_clean_name' function which is intended to safely transform a widget name (from the install.yaml, among other cases) into a string for multiple purposes.

Currently all it does is replace spaces with dashes, but it should also be stripping special characters and whatever else Fuel's Inflector::friendly_title function does.