fixed validateNumber (now E.164)

Fixed validateNumber according to http://en.wikipedia.org/wiki/E.164#Telephone_number_categories
I had a quick look at the registration process: since we do not store the users country code separately, it's impossible to handle numbers without country code.
I think we should add a country code text field to the "send to box" and also store the users country code during registration process (could be used as the default value of the cc field)...
We should definitely not let the user enter numbers without country code.