Enhance PyU4V error when attempting connection with bad credentials

[benoit-fabre-dell]

Hello,

While attempting to logging to Unisphere with wrong credentials, the SDK raised an error message which may lead to confuse with networking issue, see the error below:

The GET request to URL https://pmax:8443univmax/restapi/version timed-out, but may have been successful. Please check Unisphere Server for any slowness, long-running API calls are a symptom of Unisphere Server limits being reached. HTTPSConnectionPool(host=’pmax, port=8443): Read timed out. (read timeout=120). See https://developer.dell.com/apis/4458/versions/10.0/docs/Getting%20Started/4.concurrent_operations.md, To ensure limits are not being exceeded verify the number of connections and calls in Unisphere for PowerMax under Support > Management Server Resources or using system call get_management_server_resources()
[WARNING] issue in check_ports_not_online: <class 'PyU4V.utils.exception.VolumeBackendAPIException'>: Bad or unexpected response from the storage volume backend API: Error GET None. The status code received is None and the message is None.

See code:

PyU4V/PyU4V/rest_requests.py

Line 133 in c29bb7e

except requests.Timeout as error:

We would like to request to enhance the SDK to throw a more operator friendly message when the credentials are not correct, basically diffentiating network error from authentication errors.

Thank you!