Fix a couple of issues for PHP 7.0

Author: fguillot

app/Core/Router.php

@@ -80,7 +80,7 @@ public function getPath($uri, $query_string = '')
             $path = substr($path, 0, - strlen($query_string) - 1);
         }
 
-        if ($path{0} === '/') {
+        if (! empty($path) && $path{0} === '/') {
             $path = substr($path, 1);
         }
 
@@ -218,7 +218,6 @@ public function dispatch($uri, $query_string = '')
             list($this->controller, $this->action) = $this->findRoute($this->getPath($uri, $query_string)); // TODO: add plugin for routes
             $plugin = '';
         }
-
         $class = empty($plugin) ? '\Controller\\'.ucfirst($this->controller) : '\Plugin\\'.ucfirst($plugin).'\Controller\\'.ucfirst($this->controller);
 
         $instance = new $class($this->container);

app/Core/Session.php

@@ -45,7 +45,9 @@ public function open($base_path = '/')
         ini_set('session.use_only_cookies', '1');
 
         // Enable strict mode
-        ini_set('session.use_strict_mode', '1');
+        if (version_compare(PHP_VERSION, '7.0.0') < 0) {
+            ini_set('session.use_strict_mode', '1');
+        }
 
         // Ensure session ID integrity
         ini_set('session.entropy_file', '/dev/urandom');