azure-events: handle exceptions in urlopen (#1496)

• azure-events: handle exceptions in urlopen

The locking in azure-events does not correctly handle some
failures.

If the metadata server is not recheable or has an error
handling the request, attr_globalPullState will never go
back to IDLE unless the administrator manually changes it.

azure-events: ERROR: [Errno 104] Connection reset by peer
lrmd[2734]: notice: rsc_azure-events_monitor_10000:113088:stderr [ ocf-exit-reason:[Errno 104] Connection reset by peer ]