Ignore uris

Does fixes things: In the case of `rebase`, it would clobber the consecutive slashes in a data uri. The newly added test case would fail. And, in the case of `inline` it's really annoying to see all the warnings when it's trying to match existing data uris as files.

cc: @MoOx
I would prefer explicit test for `data:`.
What about `/^(?:[a-z]+:\/|data:.*)?\//` or something like that ?
A protocol is clearly `something://` and inlined content is `data:mi/me`.
This sould be explicit in the regex don't you think ?