Inspect permissions shows incorrect results for mixed-case groups or users

Issue Summary

Any users or groups with uppercase characters in the username/groupname are not shown as having permissions in the inspect permissions feature. Note that such usernames and group names can only be created using external directories.

The error happens on initially loading the data at start-up, so any groups or users added during testing without a restart are ok until the cache reinitialisation.

Steps to Reproduce

When we add a group (Group1) from an external directory and give it permission to view a space, it works fine. It shows up in the inspect permissions table with an upper case G, and respects permissions updates.

1. When we do something that triggers a cache reinit (eg, re-ordering user directories), Group1 now shows up in the table as group1 with a lower case g and no longer respects permission updates. 
2. Try to give group1 permission to view a space and it doesn't show up in the table.

Expected Results

Permissions can be updated as per usual.

Actual Results

Permission update is not reflected

Workaround

None