[NOMAD-2462] SAML auth
[NOMAD-2462] SAML auth

- Added "platform" parameter to ping API.
- Added isExternalLogin function.
- Refactored external login logic into a separate function to be able to override
with custom implementation. There are no changes in the logic itself.

rhoggSugarcrm/ventana,alias-mac/ventana,yvan33/ventana,sugarcrm/ventana