sslutil: document and slightly refactor validation logic
This main purpose of this patch is to make it clearer that fingerprint
pinning takes precedence over CA verification. This will make
subsequent refactoring to the validation code easier to read.
<item>
<title>{desc|strip|firstline|strip|escape}</title>
<link>{urlbase}{url|urlescape}log{node|short}/{file|urlescape}</link>
<description><![CDATA[{desc|strip|escape|websub|addbreaks|nonempty}]]></description>
<author>{author|obfuscate}</author>
<pubDate>{date|rfc822date}</pubDate>
</item>