cleanup model relationship references

app/Models/User.php

@@ -91,9 +91,9 @@ class User extends Authenticatable
      */
     public function getGravatarAttribute()
     {
-        $size = 80;
-        $default = 'https://en.gravatar.com/userimage/12856995/7c7c1da6387853fea65ff74983055386.png';
-        return 'https://www.gravatar.com/avatar/' .
+        $size = config('gravatar.size');
+        $default = config('gravatar.default');
+        return config('gravatar.url') .
                 md5(strtolower(trim($this->email))) . '?d=' . urlencode($default ) . '&s=' . $size;
     }
 
@@ -103,36 +103,36 @@ class User extends Authenticatable
 
     public function airline()
     {
-        return $this->belongsTo('App\Models\Airline', 'airline_id');
+        return $this->belongsTo(Airline::class, 'airline_id');
     }
 
     public function home_airport()
     {
-        return $this->belongsTo('App\Models\Airport', 'home_airport_id');
+        return $this->belongsTo(Airport::class, 'home_airport_id');
     }
 
     public function current_airport()
     {
-        return $this->belongsTo('App\Models\Airport', 'curr_airport_id');
+        return $this->belongsTo(Airport::class, 'curr_airport_id');
     }
 
     public function last_pirep()
     {
-        return $this->belongsTo('App\Models\Pirep', 'last_pirep_id');
+        return $this->belongsTo(Pirep::class, 'last_pirep_id');
     }
 
     public function bids()
     {
-        return $this->hasMany('App\Models\UserBid', 'user_id');
+        return $this->hasMany(UserBid::class, 'user_id');
     }
 
     public function pireps()
     {
-        return $this->hasMany('App\Models\Pirep', 'user_id');
+        return $this->hasMany(Pirep::class, 'user_id');
     }
 
     public function rank()
     {
-        return $this->belongsTo('App\Models\Rank', 'rank_id');
+        return $this->belongsTo(Rank::class, 'rank_id');
     }
 }