Limit number of environments

Since there are some query patterns that are inherently N+1 given the way our permission system works, we should soft limit the number of environments users can create to partially mitigate this impact.

This morning @matthewelwell ran some queries in production and it turns out we have active users that have huge numbers of environments (in the thousands). So whatever limit we put into place will have to grandfather in the existing clients since they're already operating above them.

The suggested limit is to put it at 100 and perhaps we should build in the ability to grant more limits for users that really want them.