server: Run start() with a generous timeout by default

The 10 second CloudManager default is not quite sufficient here.

Author: scop

upcloud_api/server.py

@@ -160,14 +160,14 @@ def stop(self):  # noqa
         """
         self.shutdown()
 
-    def start(self):
+    def start(self, timeout=120):
         """
         Start the server. Note: slow and blocking request.
 
         The API waits for confirmation from UpCloud's IaaS backend before responding.
         """
         path = '/server/{0}/start'.format(self.uuid)
-        self.cloud_manager.post_request(path)
+        self.cloud_manager.post_request(path, timeout=timeout)
         object.__setattr__(self, 'state', 'started')
 
     def restart(self, hard=False, timeout=30, force=True):