Allow dotfiles to be ignored in file serving functions

[EvanHahn]

This PR adds a :dotfiles? option which allows files that begin with . to be ignored by routes/files and routes/resources.

This is inspired by an option from Express.js's static file middleware.

[EvanHahn]

Anything I can do to get this merged? No worries if not.

[weavejester]

Sorry, this slid off my todo list. I think rather than having a single option, it would make more sense to have a predicate function instead.

[EvanHahn]

Good idea. I'll do that when I get a chance.

[EvanHahn]

I believe I've addressed comments—dotfiles? is now a function.

[weavejester]

Can you change the :dotfiles? option to :exclude instead? The reason for using a function rather than making it a boolean option is to allow for more complex exclusions. So rather than:

(resources "/" {:dot-files? false})

We can write:

(resources "/" {:exclude dot-file?})

Alternatively, I'm wondering about a syntax like:

(-> (resources "/") (exclude dot-file?))

So we'd have a generic exclude route wrapper, though that does mean that we can't have defaults, which in this case might be useful (excluding dot-files is a good default to have).

[EvanHahn]

Hmm, interesting. That first idea seems like it might be worth adding to this PR but the second seems pretty separate (not that it's not worth doing). Your thoughts?

[weavejester]

I think having an :exclude option is best, as that way it can default to dot-file?

[EvanHahn]

Okay. I'll give that a go (again, might be a bit before I can get to it).

[EvanHahn]

Do you want me to make :exclude dot-file? a default? That'd be a potentially breaking change which is why I hesitate.

[weavejester]

Let's not make it a default initially, as you're right that that would be a breaking change.

[EvanHahn]

Created #180 to replace this pull request.