FileCollection is a memory loss, not a memory win.

The file type used the FileCollection object to try and reduce memory
consumption by deduplicating path strings.

Unfortunately, this had the opposite effect in the real world, even when many
duplicate paths were present - it cost about 1.5MB extra memory in my tests.

It also costs non-trivial CPU time reconstituting the original path every time
we need to interact with that, and we do that a bunch.

So, just ditch the entire thing and move folks to just using paths directly.

Signed-off-by: Daniel Pittman <daniel@puppetlabs.com>

Conflicts:
spec/unit/type/file_spec.rb

Signed-off-by: Daniel Pittman <daniel@puppetlabs.com>