gallery3: multiple vulnerabilities

From the Gallery release notes:

After several extensive internal and external security audits which discovered 22 distinct vulnerabilities, we are releasing Gallery 3.0.4 as a security release. All of the issues require that someone with malicious intent either have an account with edit permissions, or trick a user with edit permissions into clicking on a malicious link. In most cases, this can only lead to a possible XSS vulnerability, but in several instances it allows arbitrary PHP code execution.