Add support for ServiceBus bindings

Fixes: #133

Author: elprans

tests/servicebus_functions/put_message_return/__init__.py

@@ -0,0 +1,5 @@
+import azure.functions as azf
+
+
+def main(req: azf.HttpRequest) -> bytes:
+    return req.get_body()

tests/servicebus_functions/put_message_return/function.json

@@ -0,0 +1,19 @@
+{
+  "scriptFile": "__init__.py",
+  "disabled": false,
+
+  "bindings": [
+    {
+      "type": "httpTrigger",
+      "direction": "in",
+      "name": "req"
+    },
+    {
+      "direction": "out",
+      "name": "$return",
+      "queueName": "testqueue-return",
+      "connection": "AzureWebJobsServiceBusConnectionString",
+      "type": "serviceBus"
+    }
+  ]
+}