Move account verification logic to own folder

Move the account verification email config and template to the
account_verification file in server/email
Fix meteor.user.email bug

sendMessage function now correctly uses Meteor.user().emails[0].address
Update meteor methods to return error numbers

addContact and sendMessage now return an error message.
Update sendMessage to accept a contact._id

sendMessage now receives a to_id instead of a to (email).

also updated the send message form to attach handlers only to the form
submit event.