New autocomplete for adding users to a site #341

#341 

###### Major Changes
- New user autocomplete setup.
- Allows searching by name, email, user
- Returns firstname lastname (uname, email) if f/l name is available, if not, it returns username (email)
- New autocomplete is used in the form to add users to a site as well as during vsite registration on behalf of another
- Current group member are removed from the autocomplete results.
- User1 is also removed from the autocomplete results. 

###### Minor Changes (mostly text)
- + Add a new user => + Add a user to your website
- User name => User
- Type in a persons username to search for their account. => Type in a persons name, login, or e-mail address to search for their account.
- If you can't find their account, click "Add a new user" to create a new account. => If you can't find their account, click "Create a new user" to create a new account.
- ADD AN EXISTING USER TO $vsite->title => ADD AN EXISTING USER TO THIS WEBSITE

##### Notes:
- I kept the text "If you can't find their account, click "Create a new user" to create a new account." at the bottom of the form, the issue requested it be removed, but I see it more of a helpful note to users rather than a nuance.  
 -- One argument for keeping the text would be if you knew for certain that a user didn't not have an account already, why make that user have to search for a non-existant account just to have the create account text appear?  
- I think the removing the password fields from the user creation form should be moved into it's own ticket since it's using drupal's standard user_registration form.