Throw an error if user put an invalid port range in config file

Fix #117

gns3server/modules/port_manager.py

@@ -140,7 +140,7 @@ class PortManager:
         """
 
         if end_port < start_port:
-            raise Exception("Invalid port range {}-{}".format(start_port, end_port))
+            raise HTTPConflict(text="Invalid port range {}-{}".format(start_port, end_port))
 
         if socket_type == "UDP":
             socket_type = socket.SOCK_DGRAM

gns3server/modules/project.py

@@ -152,7 +152,7 @@ class Project:
             try:
                 shutil.rmtree(old_path)
             except OSError as e:
-                raise aiohttp.web.HTTPConflict("Can't remove temporary directory {}: {}".format(old_path, e))
+                raise aiohttp.web.HTTPConflict(text="Can't remove temporary directory {}: {}".format(old_path, e))
 
     @property
     def name(self):