Fix broken link to squash icon used in commandImages extension

We have a new png squash icon so use it to fix broken link to the old
gif icon which was deleted.

Change-Id: I1b0c626094ac4df1de4a14605dc74a059d7922d1
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Merge "Fix broken link to squash icon used in commandImages extension"