Small fixes (SSL host verification and non-URL Location headers)

Hello,

This pull request addresses two bugs I have found in my own installation (TinyTinyRSS version 1.11).

The first is an SSL verfication failure that occurs with self-signed certificates.  I addressed a similar issue in an earlier pull request (#212), but it seems that there was some sort of bug in cURL that caused the `CURLOPT_SSL_VERIFYHOST` to be ignored if `CURLOPT_SSL_VERIFYPEER` was turned off (http://curl.haxx.se/docs/adv_20131217.html).  This bug was fixed in cURL 7.34.0, so if TinyTinyRSS is being used with this version of cURL or later, it will fail on feeds using self-signed certificates.  So the first commit turns off the `CURLOPT_SSL_VERIFYHOST` feature.  This should probably be settable on a per-feed basis.

The second is a problem with 302 redirects and the `Location` header if the header is not a URL.  Some sites (in my case, GitHub pages) send back a relative or absolute URL fragment to be intrepreted with respect to the original URL.  The second and third commits address this scenario.

I don't write a lot of PHP, so please let me know if the code needs cleaning up.