Previously, specfiles would get read then normalized. We want
specfiles to be normalized on read so there is no confusion about
what the format of specfiles should be.
This commit validates the parsed result of --specfile. If entries
aren't prefixed, an error is raised.
Previously, validation would occur at exchange time, hence why we
dropped a line of test output related to server iteraction.
Maybe "file:" was just a typo for "path:" so it's better to replace it by "path:" (instead of having both)?