Extending MENU configuration key functionality

[nnseva]

Changes here make the following extensions:

1. Case-insensitive model and application names in the menu config key (useful in case of migration to the suit config from another admin dashboard applications)
2. Globbing model names by asterick in the 'models' key (useful when uniting several applications in one new custom application)
3. Extending model descriptor (passed to the get_menu template tag) by the separate add_url and perms keys (useful in case of extending suit templates)
4. Documentation of the new config functions

[SalahAdDin]

👍

[nnseva]

All fixed

[darklow]

Very nice thank you for fixes!