feat: enable Paketo builders for Python functions (#979)

This commit changes the Python functions to use the open source Paketo
builders. The Paketo builders allow the use of a Procfile to indicate
the desired default start process for the container, so this has been
added to invoke Parliament at startup.

Also, there were no README.md files for Python, so I added them too.

Signed-off-by: Lance Ball <lball@redhat.com>

buildpacks/builder.go

@@ -25,6 +25,7 @@ var DefaultBuilderImages = map[string]string{
 	"node":       "gcr.io/paketo-buildpacks/builder:base",
 	"typescript": "gcr.io/paketo-buildpacks/builder:base",
 	"go":         "gcr.io/paketo-buildpacks/builder:base",
+	"python":     "gcr.io/paketo-buildpacks/builder:base",
 }
 
 //Builder holds the configuration that will be passed to

templates/python/cloudevents/Procfile

@@ -0,0 +1 @@
+web: python -m parliament .

templates/python/cloudevents/README.md

@@ -0,0 +1,29 @@
+# Python CloudEvents Function
+
+Welcome to your new Python function project! The boilerplate function
+code can be found in [`func.py`](./func.py). This function is meant
+to respond to [Cloud Events](https://cloudevents.io/).
+
+## Endpoints
+
+Running this function will expose three endpoints.
+
+  * `/` The endpoint for your function.
+  * `/health/readiness` The endpoint for a readiness health check
+  * `/health/liveness` The endpoint for a liveness health check
+
+The health checks can be accessed in your browser at
+[http://localhost:8080/health/readiness]() and
+[http://localhost:8080/health/liveness]().
+
+You can use `func invoke` to send an event to the function endpoint.
+
+
+## Testing
+
+This function project includes a [unit test](./test_func.py). Update this
+as you add business logic to your function in order to test its behavior.
+
+```console
+python test_func.py
+```

templates/python/http/Procfile

@@ -0,0 +1 @@
+web: python -m parliament .

templates/python/http/README.md

@@ -0,0 +1,29 @@
+# Python HTTP Function
+
+Welcome to your new Python function project! The boilerplate function
+code can be found in [`func.py`](./func.py). This function will respond
+to incoming HTTP GET and POST requests.
+
+## Endpoints
+
+Running this function will expose three endpoints.
+
+  * `/` The endpoint for your function.
+  * `/health/readiness` The endpoint for a readiness health check
+  * `/health/liveness` The endpoint for a liveness health check
+
+The health checks can be accessed in your browser at
+[http://localhost:8080/health/readiness]() and
+[http://localhost:8080/health/liveness]().
+
+You can use `func invoke` to send an HTTP request to the function endpoint.
+
+
+## Testing
+
+This function project includes a [unit test](./test_func.py). Update this
+as you add business logic to your function in order to test its behavior.
+
+```console
+python test_func.py
+```