Email validation and other changes

-Added functionality for registering accounts.  Now checks for email format (_@_._) before adding to user table.  Also checks for password min/max length requirement. (currently set to 4-24 characters)

-Note: All usernames/friends in table that did not meet the email requirement (i.e: username: aaa) have been cleaned out of the database table.

-Simplified client code to use json "messages" instead of creating its own.  updated add friend, and login page to do this.  Register account still needs a textView to show json "message" when a failed attempt at registering is made.  "to do" marked in client code where it needs to be.