Added role based MFA control

- Added new DB column for control and role updated create/update actions.
- Created new middleware as a start to actual enforcement logic.
- Added indicator to role list of whether MFA is enforced.

app/Http/Middleware/EnforceMfaRequirements.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace BookStack\Http\Middleware;
+
+use Closure;
+
+class EnforceMfaRequirements
+{
+    /**
+     * Handle an incoming request.
+     *
+     * @param  \Illuminate\Http\Request  $request
+     * @param  \Closure  $next
+     * @return mixed
+     */
+    public function handle($request, Closure $next)
+    {
+        $mfaRequired = user()->roles()->where('mfa_enforced', '=', true)->exists();
+        // TODO - Run this after auth (If authenticated)
+        // TODO - Redirect user to setup MFA or verify via MFA.
+        // TODO - Store mfa_pass into session for future requests?
+        return $next($request);
+    }
+}