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
For me I will merge similar logics together:

```
    void hashInsert(const std::string& key) {
      val = g_new0(GValue, 1);
      g_value_init(val, G_TYPE_STRING);
      g_value_set_string(val, obj.get(key.c_str()).to_str().c_str());
      g_hash_table_insert(data_, g_strdup(key.c_str()), val);
    }

    if (key == "username" ||
        key == "secret" ||
        key == "realm" ||
        key == "networkProxy" ) {
      hashInsert(key);
    }
```