Update ft.picture.php

Added a new var called 'image_size' which returns 'thumb', 'sized' or 'orginal' depending upon the outcome of lines 507 through 521.
Merge pull request #15 from nathanpitman/patch-1

Update ft.picture.php by Nathan Pitman

Added a new var called 'image_size' which returns 'thumb', 'sized' or 'orginal' depending upon the outcome of lines 507 through 521.