Fix command processing to check for equality

The selection on which command was executed used a startswith check. When we have multiple commands that start with the same name, the wrong one might be selected.
In this PR we extract the first token instead and check for equality.

api/slack/commands.py

@@ -63,10 +63,15 @@ def process_message(data: Dict) -> None:
         "dadjoke": dadjoke_cmd,
     }
 
-    for key in options.keys():
-        if message.startswith(key):
-            options[key](channel, message)
-            return
+    tokens = message.split()
+
+    if len(tokens) > 0:
+        # Find the command corresponding to the message
+        cmd_name = tokens[0].casefold()
+        for key in options.keys():
+            if cmd_name == key:
+                options[key](channel, message)
+                return
 
     # if we fall through here, we got a message that we don't understand.
     client.chat_postMessage(