Another config option on my quest to a `*_path` variant for every
secret. Adds the config options `recaptcha_private_key_path` and
`recaptcha_public_key_path`. Tests and docs are included.
A public key is of course no secret, but it is closely related to the
private key, so it’s still useful to have a `*_path` variant for it.
You can now configure how much media can be uploaded by a user in a
given time period.
Note the first commit here is a refactor of create/upload content
function
