Remove openid_cp_field dependency and move content_profile parts into openid_cp_field

Openid_client_ax should be similar to openid_provider_ax in the whole concept.
So I introduced these instead of calling openid_cp_field functions directly:
module_invoke_all('openid_client_ax', 'save', $response, $account);
$mapping = module_invoke_all('openid_client_ax', 'get');

This means I could remove all content_profile depending code from the module.
Please don't commit yet. Needs more work. (altough it looks promising)
I see one issue here: if i login using the same openid second time, i get a white page. altough if i go to the front page, i logged in, so the authentication happens fine.