Guest tag is now 3 instead of 2.
Remove SSL version 3 support.

This commit mirrors Hopu-Ka-Lewa-website commit de82f186ceaf003df3460aa88cae18f361447686.

Per the original IPN listener author's repo pull request 32: [Quixotix/PHP-PayPal-IPN#32](https://github.com/Quixotix/PHP-PayPal-IPN/pull/32).
(This pull request had not yet been pulled into the original repo at the time of this edit.)

PayPal has stopped supporting SSLv3, so we have to as well.
Update IPN for KK28.

Change master spreadsheet key.
Change guest ID from 2 to 3.