Merge pull request #353 in ZP/z-push from bugfix/ZP-806-add-braces-to-force-desired-interpretation to feature/ZP-804-php-7-compatibility

* commit '0787b58d':
  ZP-806 Added curly braces {} to all calls in the format of $this->$a[b] so interpreter will treat as $this->{$a[b]}. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-806 Added curly braces {} to all calls in the format of $this->$a[b] so interpreter will treat as $this->{$a[b]}. Released under the Affero GNU General Public License (AGPL) version 3.