[Python] Adds new client generator, python-experimental (#3244)

* Adds python-experimental generator

* Adds python-experimental samples folder which uses its own v2 spec

* Adds enusre-up-to-date updates

* Removes samples/client/petstore/perl/t/AnotherFakeApiTest.t

* Removes comment line from python-experimental generator

* Reverts perl docs file

* Updates perl sample client

* Adds python-experimental to pom.xml

* Copies the python test foldeers tests and testfiles into python-experimental

* Copies python test folder into python-experimental

* Moves python testing from Travis (samples pom.xml profile) to Circlci (samples.circleci pom.xml profile)

* Adds python-experimental pom.xml

* Adds python-experimental makefile and .sh files

* Chenges python-experimental to use gitignored venv rather than .venv which is not ignored when testing

* Adds dev-requiremnts.txt and removes .travis.yml from python-experimental so CI tests will pass

* Moves python-experimental from CicleCI to Travis to get support for multiple python environments

* Updates generator java comment so CI tests will run over again

samples/client/petstore/python-experimental/docs/AnotherFakeApi.md

@@ -0,0 +1,63 @@
+# petstore_api.AnotherFakeApi
+
+All URIs are relative to *http://petstore.swagger.io:80/v2*
+
+Method | HTTP request | Description
+------------- | ------------- | -------------
+[**call_123_test_special_tags**](AnotherFakeApi.md#call_123_test_special_tags) | **PATCH** /another-fake/dummy | To test special tags
+
+
+# **call_123_test_special_tags**
+> Client call_123_test_special_tags(body)
+
+To test special tags
+
+To test special tags and operation ID starting with number
+
+### Example
+
+```python
+from __future__ import print_function
+import time
+import petstore_api
+from petstore_api.rest import ApiException
+from pprint import pprint
+
+# create an instance of the API class
+api_instance = petstore_api.AnotherFakeApi()
+body = petstore_api.Client() # Client | client model
+
+try:
+    # To test special tags
+    api_response = api_instance.call_123_test_special_tags(body)
+    pprint(api_response)
+except ApiException as e:
+    print("Exception when calling AnotherFakeApi->call_123_test_special_tags: %s\n" % e)
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **body** | [**Client**](Client.md)| client model | 
+
+### Return type
+
+[**Client**](Client.md)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: application/json
+ - **Accept**: application/json
+
+### HTTP response details
+| Status code | Description | Response headers |
+|-------------|-------------|------------------|
+**200** | successful operation |  -  |
+
+[[Back to top]](#) [[Back to API list]](../README.md#documentation-for-api-endpoints) [[Back to Model list]](../README.md#documentation-for-models) [[Back to README]](../README.md)
+