Try to improve calculation of visited urls/hour 3, a=chrisg

diff --git a/src/models/CrawlModel.php b/src/models/CrawlModel.php
index 8841c3241..127dcedbc 100755
--- a/src/models/CrawlModel.php
+++ b/src/models/CrawlModel.php
@@ -1450,7 +1450,7 @@ EOT;
                     floatval(C\ONE_HOUR);
                 $change_in_urls = $recent[1] - $oldest[1];
                 $data[$channel]['VISITED_URLS_COUNT_PER_HOUR'] =
-                    min((($change_in_time_hours > 0) ?
+                    max((($change_in_time_hours > 0) ?
                     $change_in_urls/$change_in_time_hours : 0), 0);
             } else {
                 $data[$channel]['VISITED_URLS_COUNT_PER_HOUR'] = 0;