Feature request: .htpasswd support

[tammersaleh]

I don't have the go chops to submit this myself, but I'd love to see .htpasswd support in devd. I use devd to host short-term content for training workshops, and I'd like to be able to easily give the students access to some of the content (the labs), but require basic auth password for other content (the slides). I imagine the right way of doing this is to have each in separate directories, and have an .htpasswd file in the protected directory.

[tammersaleh]

Somehow missed the -P option - sorry about that!