Disable players that have already paid.

Added new database column to indicate what method each player has paid
by.  If that method is blank (they haven't paid) or equals "FRAUD"
(they paid the wrong amount), their name will be selectable.
Otherwise, their name will appear, but won't be selectable.
Payment UI improvements.

Disable the placeholder options in the select boxes.
Also, reduce the verbage in the add/remove team buttons.
Add player names into PayPal item name.

Now the names of the players being paid for will appear as an English list in the PayPal item name field.  Error checking performed if the new item name string length exceeds the maximum allowed by PayPal.  Possible shortcoming: If the one and only (or just first) name exceeds the max string length.  No error checking is provided for this edge case.  Unclear how PayPal handles a string length error.  Probably truncates, but I don't know for sure.
Player payment copy edits.

Modified instructions for clarity and consciseness.
Slight formatting change to give the LABELs a bit more breathing room.