Fix inconsistency between model name and file name in python client

[banh-gao]

Fixes issue #7357 using the same fix as #4958

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh and ./bin/security/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\.
• Filed the PR against the correct branch: 3.0.0 branch for changes related to OpenAPI spec 3.0. Default: master.

Description of the PR

Fixes modules filename generation for the python client. Issue reported in #7357 and #4684.
The fix applied to python client generator is the same as the one applied to the Flask server in #4958.

[wing328]

@banh-gao tests (with updated samples) passed via https://travis-ci.org/swagger-api/swagger-codegen/builds/344730950

Next time, please update the Python Petstore samples by running the shell scripts or batch files under ./bin/ or .\bin\windows\

[wing328]

Python petstore samples updated via b4827be

[bedge]

This bug is present in STABLE, 2.3.1:

❯ swagger-codegen version
2.3.1

~/git/apis/bindings/bindings/models/init.py in ()
21 from bindings.models.http_endpoint import HTTPEndpoint
22 from bindings.models.map_context_root import MapContextRoot
---> 23 from bindings.models.model_property import ModelProperty
24 from bindings.models.module import Module
25 from bindings.models.node import Node

~/git/apis/bindings/bindings/models/model_property.py in ()
16 import six
17
---> 18 from bindings.models.object import Object # noqa: F401,E501

3.0.0 claims no python code generators:

https://github.com/swagger-api/swagger-codegen/releases:

java and inflector are the only supported languages.

Is there a functional tag one can use for python in the interim?

[samohant]

Module not found for 'swagger_client.model.errorunknown' in swagger_client python