Implementation of Tizen SSO APIs

Implementation of SSO APIs as per widl file https://code.google.com/p/accounts-sso/source/browse/widl/signon.widl?repo=libgsignon-glib

Backend that provides core functionality is gSSO and more information about that
component could be found at https://01.org/gsso
I'm not so sure I mentioned this before, but please do as below to avoid too long code in the if clause.

```
  if (!IsSupportedType(type))
    return;

  switch (type) {
  ...
  }
```