Support searching both staff and user backends via a common interface.

Previously we required an account to associate a user to an organization.

If a remote user is found by name and does not have an email address, a bad
SQL query would be generated

Fixup search for users with hits in an searchable authentication backend:

  * If there is a hit for the remote backend, include that in the search for
    local users by email address. If there is a hit locally for the same
    email address, then remove the remote hit from the search results.

Fixup typeahead results

  * Abort previous search requests when the user enters more text into the
    search fields. This makes the search box feel more consistent, and
    avoids the case where the user finishes typing and valid search hits
    never appear

Requires authentication plugins to implement a new AuthDirectorySearch
interface to define the two functions

Displaying field values on various pages and dialogs could result in cross
site scripting exploits.

Fixes osTicket/osTicket-1.8#296

Previously, the user information could only be modified on the ticket-view
page. For instance, if creating a new ticket for a user, no new information
could be added or modified on the user until after the ticket was created

Fixes osTicket/osTicket-1.8#281

This includes the initial concept of pluggable authentication along with the
initial concept for a plugin management system.

Change fromForm routine takes the actual form and do validation and call
fromVars with clean data

Add fromVars to do the actual user creation (previously named fromForm.

Include all validation erors

Include all validation erors

- Remove Client form
- Provide name and email fields for cases where use is not selected (JS
issues)

Fix odd CSS error

Allows the client to be changed on a ticket. Previously, only the
information about the client associated with the ticket was editable. This
patch permits assigning a completely different user to the ticket.

This moves client information like name and email address out of the general
dynamic forms data for a ticket. It really paves the way for the first-class
user of the future.