Fixing a bug with the model's connection

`$this->connection` doesn't respect changes that may have occurred to the model's database connection.  Multi-tenancy packages for example commonly change the model's connection.

Author: ChrisThompsonTLDR

src/Kodeine/Metable/Metable.php

@@ -351,7 +351,7 @@ public function setAttributes(array $attributes) {
      * @return boolean
      */
     public function hasColumn($column) {
-        if(empty(self::$_columnNames)) self::$_columnNames = array_map('strtolower',\Schema::connection($this->connection)->getColumnListing($this->getTable()));
+        if(empty(self::$_columnNames)) self::$_columnNames = array_map('strtolower',\Schema::connection($this->getConnectionName())->getColumnListing($this->getTable()));
         return in_array(strtolower($column), self::$_columnNames);
     }