[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/setup.py

@@ -0,0 +1,39 @@
+# coding: utf-8
+
+"""
+    OpenAPI Petstore
+
+    This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\  # noqa: E501
+
+    The version of the OpenAPI document: 1.0.0
+    Generated by: https://openapi-generator.tech
+"""
+
+
+from setuptools import setup, find_packages  # noqa: H301
+
+NAME = "petstore-api"
+VERSION = "1.0.0"
+# To install the library, run the following
+#
+# python setup.py install
+#
+# prerequisite: setuptools
+# http://pypi.python.org/pypi/setuptools
+
+REQUIRES = ["urllib3 >= 1.15", "six >= 1.10", "certifi", "python-dateutil"]
+
+setup(
+    name=NAME,
+    version=VERSION,
+    description="OpenAPI Petstore",
+    author_email="",
+    url="",
+    keywords=["OpenAPI", "OpenAPI-Generator", "OpenAPI Petstore"],
+    install_requires=REQUIRES,
+    packages=find_packages(),
+    include_package_data=True,
+    long_description="""\
+    This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\  # noqa: E501
+    """
+)