Fixed one typo in response_helpers which caused is_admin context variable not to work correctly.
Created new checkLinkNameForId function that checks if link_name is correct when creating new user and modifying existing one. This is now used for validation instead of doesLinkNameBelongToId in UserForm clean_link_name function. The previous validation function didn't allow to create new users and modify linkname of existing ones. Additionally I created new doesLinkNameExist helper function.
Fixed wrong user variable in lookup.html template for edit link (was user should be found_user).
There is no DeveloperForm in site/user/profile.py changed that to LookupForm.