perm: Allow adding groups with some uppercase letters with `trac-admin $ENV permission add`, and prevent creating all-uppercase users and groups.
perm: Allow adding groups with some uppercase letters with `trac-admin $ENV permission add`, and prevent creating all-uppercase users and groups.

Closes #9279.


git-svn-id: f68c6b3b1dcd5d00a2560c384475aaef3bc99487@9593 af82e41b-90c4-0310-8c96-b1721e28e2e2

moreati/trac-gitsvn,dafrito/trac-mirror,exocad/exotrac,moreati/trac-gitsvn,dafrito/trac-mirror,exocad/exotrac,exocad/exotrac,dafrito/trac-mirror,dafrito/trac-mirror,exocad/exotrac,moreati/trac-gitsvn,moreati/trac-gitsvn