[ticket/11145] Wrong error thrown when uploading a bigger image.

When attaching an image to a post with a size larger than maximum defined in
php.ini, 'ATTACHED_IMAGE_NOT_IMAGE' error is thrown. $file->is_image() is
returning false value when image size is too large. Therefore, moved
not image test down after image size test.

PHPBB3-11145
[ticket/10840] Add check_form_key to acp_groups.php

PHPBB3-10840
[ticket/11122] Remove Oleg and igorw from active authors

PHPBB3-11122
[ticket/11122] Add dhruv to active authors

PHPBB3-11122
Merge remote-tracking branch 'nickvergessen/ticket/11122-2' into develop-olympus

* nickvergessen/ticket/11122-2:
  [ticket/11122] Add dhruv to active authors
  [ticket/11122] Remove Oleg and igorw from active authors
Merge remote-tracking branch 'nickvergessen/ticket/10840' into develop-olympus

* nickvergessen/ticket/10840:
  [ticket/10840] Add check_form_key to acp_groups.php
Merge remote-tracking branch 'erangamapa/ticket/11145' into develop-olympus

* erangamapa/ticket/11145:
  [ticket/11145] Wrong error thrown when uploading a bigger image.