Use alpine python and gunicorn

Adding docker_settings.py which reads environment variables
to allows for environment variable to be passed to the
container

requirements-docker.txt

@@ -0,0 +1,10 @@
+gunicorn==19.6.0
+Flask==0.10.1
+Flask-WTF==0.12
+Jinja2==2.7.2
+MarkupSafe==0.19
+WTForms==2.1
+Werkzeug==0.11.10
+itsdangerous==0.23
+pypuppetdb==0.3.1
+requests==2.6.0