Support for aliases that are folders of packages

It is possible to require a file that is path of a package that is installed via npm like
require("jade/lib/filters")
this patch should make that possible.
Merge branch 'patch-1' of github.com:martinheidegger/aliasify into martinheidegger-patch-1

Conflicts:
	src/aliasify.coffee
v1.2.0