Merge branch 'master' into 2.0

gns3server/compute/base_node.py

@@ -452,11 +452,7 @@ class BaseNode:
         """
 
         path = self._manager.config.get_section_config("Server").get("ubridge_path", "ubridge")
-        if path == "ubridge" or path == "None":
-            path = shutil.which("ubridge")
-
-        if path is None or len(path) == 0:
-            raise NodeError("uBridge is not installed")
+        path = shutil.which(path)
         return path
 
     @asyncio.coroutine
@@ -481,7 +477,7 @@ class BaseNode:
         """
 
         if self.ubridge_path is None:
-            raise NodeError("uBridge is not available")
+            raise NodeError("uBridge is not available or path doesn't exist")
 
         if not self._manager.has_privileged_access(self.ubridge_path):
             raise NodeError("uBridge requires root access or capability to interact with network adapters")