Check corobo rights on all gitter rooms

Very closely related to #412 and #462 ...

corobo needs to check it has sufficient permission to ban in each of those gitter rooms. We've found the gitter permission system to be quite convoluted, as it has a mix of GitHub and Gitter permissions. Also it is easy to create a new room and forget to set up the permissions so that the bot is able to operate correctly, such as activating a ban if required.

The check might be part of the bot , if there is a delayed job. We wouldnt want this check running every startup, and not on developer builds. Another approach would be to have a script that can be run by a cron job to detect the bot has sufficient rights.

Read related issues #412 and #462 first to understand the existing room-permission work. Then trace how corobo handles Gitter rooms and whether a delayed job or runnable script fits the proposal. Done means checking ban permission in every room without running on startup or developer builds, with a cron-compatible detection path.

Written by the indexing model from the issue text.