No redirect follow on HEAD request (bump to PHP5.5 minimum requirement)

We're using the try-catch-finally clause where "finally" wasn't introduced
until PHP 5.5, so our minimum requirement for GNU social is bumped to that.

INSTALL

@@ -26,7 +26,7 @@ PHP modules
 The following software packages are *required* for this software to
 run correctly.
 
-- PHP 5.4+      For newer versions, some functions that are used may be
+- PHP 5.5+      For newer versions, some functions that are used may be
                 disabled by default, such as the pcntl_* family. See the
                 section on 'Queues and daemons' for more information.
 - MariaDB 5+    GNU Social uses, by default, a MariaDB server for data

lib/httpclient.php

@@ -103,7 +103,7 @@ class GNUsocial_HTTPResponse extends HTTP_Request2_Response
  *
  * This extends the PEAR HTTP_Request2 package:
  * - sends StatusNet-specific User-Agent header
- * - 'follow_redirects' config option, defaulting off
+ * - 'follow_redirects' config option, defaulting on
  * - 'max_redirs' config option, defaulting to 10
  * - extended response class adds getRedirectCount() and getUrl() methods
  * - get() and post() convenience functions return body content directly
@@ -205,12 +205,28 @@ class HTTPClient extends HTTP_Request2
     /**
      * Convenience function to run a HEAD request.
      *
+     * NOTE: Will probably turn into a GET request if you let it follow redirects!
+     *       That option is only there to be flexible and may be removed in the future!
+     *
      * @return GNUsocial_HTTPResponse
      * @throws HTTP_Request2_Exception
      */
-    public function head($url, $headers=array())
+    public function head($url, $headers=array(), $follow_redirects=false)
     {
+        // Save the configured value for follow_redirects
+        $old_follow = $this->config['follow_redirects'];
+        try {
+            // Temporarily (possibly) override the follow_redirects setting
+            $this->config['follow_redirects'] = $follow_redirects;
             return $this->doRequest($url, self::METHOD_HEAD, $headers);
+        } catch (Exception $e) {
+            // Let the exception go on its merry way.
+            throw $e;
+        } finally {
+            // reset to the old value
+            $this->config['follow_redirects'] = $old_follow;
+        }
+        //we've either returned or thrown exception here
     }
 
     /**