Error handling

[Someguy123]

The tip bot currently does not warn you of various things:

• Running !tipbot tip 0.001 ltc USERNAME will just come up with nothing, because it's below the 0.002 threshold. It SHOULD say something like "Sorry Someguy123, you need to tip at least 0.002 LTC"
• Make it rain is the same. It seems to try to match the minimum LTC per user, e.g. you'd need at least 0.011 LTC if you have 10 users in your room. Again no error.
• Shapeshift dust check. Right now it sends your coins to shapeshift even if they're below the dust limit, causing coins to be lost.