Add implementation for pgsql driver.

Author: tptrixtop

src/Adapter/Driver/Pgsql/Pgsql.php

@@ -253,7 +253,9 @@ public function checkConnection(StatementInterface $statement = null)
         for ($i = 0; $i < $reconnectTries; ++$i) {
             if (pg_connection_status($pg_sql) == PGSQL_CONNECTION_OK) {
                 if ($statement instanceof Statement) {
-                    $statement->initialize($pg_sql);
+                    $statement
+                        ->initialize($pg_sql)
+                        ->prepare();
                 }
 
                 return $this;

src/Adapter/Driver/Pgsql/Statement.php

@@ -88,7 +88,7 @@ public function getProfiler()
      * Initialize
      *
      * @param  resource $pgsql
-     * @return void
+     * @return $this
      * @throws Exception\RuntimeException for invalid or missing postgresql connection
      */
     public function initialize($pgsql)
@@ -101,6 +101,7 @@ public function initialize($pgsql)
             ));
         }
         $this->pgsql = $pgsql;
+        return $this;
     }
 
     /**