more form improvements
Forms: error handling simplified
Fix role handling in auth

Use fixed string Anonymous as role in Anonymous handler
if no role name is given.
Check if a role is defined in External handler
Change handler url to connect.cgi
Add userrole to info line
Remove status code hack
Fix session handling and catch failed login
Merge remote-tracking branch 'dsiebeck/feature/webui' into feature/webui

Conflicts:
	core/webui/htdocs/js/oxi/form.js