Organizer ID can exceed maximum integer value on 32-bit installs

[andymccray]

On 32-bit builds of PHP, numbers that exceed the limits of a 32-bit integer (±2,000,000,000) are silently cast to a float. The organizer_id expects an integer. For my account, those values were all greater than that maximum number (11 digits) and silently failed. Allowing the organizer_id to be passed in as a string avoids the issue.