Add pubkey definition in meta.
Move fingerprint checks to a separate function.
Split extract and check functions for repos.
Use correct signature length for pubkeys.
Update key definition for repo meta.

Now it should look like this one:

cert = {
	type = rsa;
	data = <<EOD
<big PEM BLOB>
EOD
	name = "pkg.freebsd.org.2013102301";
}

Meta can contain more than one cert.
Added by a mistake.
Add signatures free utility.
Fix issues with the new code.
Merge branch 'pubkey-meta'