Rate-Limit certain features

Bernd should limit invocations of the pot command to e.g. once per 12 hours. In case of reinvocation on the same day, Bernd should repost the link to the already uploaded image to save memory.

This should also be implemented for:

• alarm: once per 15 Min
• cage: once per hour
• maunz: once per 15 Min
• pot: once per 5 Min