Python AIOHTTP server generator (#1470)

* Astract factory for generators based on connexion

* Add aiohttp server generator

* Fix flask tests

* Normalize python-flask folder names

samples/server/petstore/python-flask-python2/Makefile

@@ -0,0 +1,20 @@
+ #!/bin/bash
+
+REQUIREMENTS_OUT=test-requirements.txt.log
+SETUP_OUT=*.egg-info
+VENV=.venv
+
+clean:
+		rm -rf $(REQUIREMENTS_OUT)
+		rm -rf $(SETUP_OUT)
+		rm -rf $(VENV)
+		rm -rf .tox
+		rm -rf .coverage
+		find . -name "*.py[oc]" -delete
+		find . -name "__pycache__" -delete
+
+test: clean
+		bash ./test_python2.sh
+
+test-all: clean
+		bash ./test_python2.sh