fixed validateNumber (now E.164)

Fixed validateNumber according to http://en.wikipedia.org/wiki/E.164#Telephone_number_categories
re: registration: sure, makes sense that we should store the user's country code for easier access later.
However, I see no reason why we cant let users enter numbers without a country code (what dialer app does that?).

The way I envisioned it:
 * During registration, store user's country code (I think there is actually a well-defined standard for splitting out country code from a number, though possibly you need to keep track of the set of possible country codes so its probably just easier to store it).
 * For sending, allow free-form text input and have a function (ie verifyNumber) that tries to normalize it and guess things like country code. If the number does not start with a + (0 in the us, so we need to replace an initial 0 with a +), they probably didnt enter a country code. If it starts with a +, or some other special code depending on their local phone dialing codes (see, maybe http://en.wikipedia.org/wiki/Trunk_prefix), clean it up and use that.