CLC-2495 Reset external apps on Canvas beta/test servers

https://jira.media.berkeley.edu/jira/browse/CLC-2889

Function, Rake task, & shell script for a cronjob to check multiple Canvas servers for overwritten CalCentral-implemented tasks, & to reset their configurations as needed to point to the correct server.

Hard to make this one look pretty. Firewalls keep the relevant Canvas servers from reaching their assigned CalCentral servers. (Embedded apps still work because the *browser* is able to reach both the Canvas & the CalCentral server.) This means that another, reachable CalCentral server needs to be able to configure the apps to point to the right places. It also means that this approach only works if the overwritten configurations are very stable except for their URL hosts. Luckily, that's the case. (If/when we need a major re-configuration of an already installed app on an overwritten development/QA server, we'll need to handle it manually.)

Confused? I don't blame you, & would be happy to whiteboard it.