added event filters

Added the capability of specifying an array of filters during event registration.
Filters are specified as regular expressions.

Example:
$client->registerEventListener(
    function($event) {var_dump($event);},
    array(
        'event' => '/Hangup/',
        'channel' => '/Local\/27.*/',
   )
);

Cherry-Picked b442e8c from @sctt (marcelog#107)

src/PAMI/Client/Impl/ClientImpl.php

@@ -337,9 +337,12 @@ protected function dispatch(IncomingMessage $message)
         foreach ($this->eventListeners as $data) {
             $listener = $data[0];
             $predicate = $data[1];
-            if (is_callable($predicate) && !call_user_func($predicate, $message)) {
+
+            if (!$this->evaluatePredicate($predicate, $message))
+            {
                 continue;
             }
+
             if ($listener instanceof \Closure) {
                 $listener($message);
             } elseif (is_array($listener)) {
@@ -350,6 +353,33 @@ protected function dispatch(IncomingMessage $message)
         }
     }
 
+    /**
+     * Evaluate a predicate for a message.
+     *
+     * @param $predicate a closure or an array of filters.
+     * @param \PAMI\Message\IncomingMessage $message Message to compare.
+     *
+     * @return bool
+     */
+    protected function evaluatePredicate($predicate, IncomingMessage $message)
+    {
+        if (is_callable($predicate)) {
+            return call_user_func($predicate, $message);
+        }
+
+        if (!is_array($predicate)) {
+            return true;
+        }
+
+        foreach ($predicate as $key => $value) {
+            if (!preg_match($value, $message->getKey($key))) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
     /**
      * Returns a ResponseMessage from a raw string that came from asterisk.
      *