Fundraising tech/Paymentswiki upgrade

The processes to upgrade paymentswiki should be something like:

Schema upgrade required

 * Confirm a recent database backup.
 * Disable campaigns.
 * Disable paymentswiki using LocalSettings variable.
 * Update the code to the new release.
 * Enable writability on the master wiki database (payments1001)
 * Login to payments1001, cd to the wiki root directory, and run "php maintenance/update.php".
 * Reenable paymentswiki and test.
 * Reenable campaigns.
 * Watch logs for 1 hr.

Risky, but code-only changes

 * Disable campaigns.
 * Disable paymentswiki using LocalSettings variable.
 * Update the code to the new release.
 * Reenable paymentswiki and test.
 * Reenable campaigns.
 * Watch logs for 1 hr.

Safe, code-only changes

 * Update the code to the new release.
 * Watch logs for 1 hr.