bots: Move contrib_bots to api/bots*.

This will make it convenient to include these bots in Zulip API
releases on pypi.

Fix #5009.

bots/followup/followup.py

@@ -0,0 +1,46 @@
+# See readme.md for instructions on running this code.
+
+class FollowupHandler(object):
+    '''
+    This plugin facilitates creating follow-up tasks when
+    you are using Zulip to conduct a virtual meeting.  It
+    looks for messages starting with '@mention-bot'.
+
+    In this example, we write follow up items to a special
+    Zulip stream called "followup," but this code could
+    be adapted to write follow up items to some kind of
+    external issue tracker as well.
+    '''
+
+    def usage(self):
+        return '''
+            This plugin will allow users to flag messages
+            as being follow-up items.  Users should preface
+            messages with "@mention-bot".
+
+            Before running this, make sure to create a stream
+            called "followup" that your API user can send to.
+            '''
+
+    def handle_message(self, message, client, state_handler):
+        if message['content'] == '':
+            bot_response = "Please specify the message you want to send to followup stream after @mention-bot"
+            client.send_reply(message, bot_response)
+        else:
+            bot_response = self.get_bot_followup_response(message)
+            client.send_message(dict(
+                type='stream',
+                to='followup',
+                subject=message['sender_email'],
+                content=bot_response,
+            ))
+
+    def get_bot_followup_response(self, message):
+        original_content = message['content']
+        original_sender = message['sender_email']
+        temp_content = 'from %s: ' % (original_sender,)
+        new_content = temp_content + original_content
+
+        return new_content
+
+handler_class = FollowupHandler