Revert to simpler implementation from upstream
Re-indent
Add check for URLs as rpm_gpgkey path
Add support for relative paths to key files
Downcase keyid
Delint.
Only downcase() if $keyid is a string.

If the key IDs are not quoted in Hiera's YAML, then all base 10 digit
key IDs will be cast as integers rather than strings. downcase() doesn't
like that.

I've explicitly stringified all key IDs in Hiera, but let's
invoke Postel's law here.
Use Wil's explicit way of ensuring keyid is a str

Adding a loquacious comment as to prevent my future self from removing
quotes from $keyid, as puppet-lint complains about "string containing
only a variable".
Add doc to define
Add copyright & license
Add README