Update re: The "arbitrary uploads" issue.

a. Remember, this is only an issue if your Admin logins are already compromised.

b. Code to protect against it has been added to v1.5.5

c. For those wanting to patch v1.5.4 and older, the changes shown in each of these links can be applied manually:
- https://github.com/zencart/zencart/c...a85e91258f?w=0
- https://github.com/zencart/zencart/c...b71008073ff8ea