In CustomExecute steps, give ability to ignore certain errors

[ha.nadine]

Currently, there is an option to ignore all errors in a customExecute step.

However, if you are including an installer as a step, sometimes it returns code 3010 (which isn't an actual error). It would be helpful to be able to ignore the 3010 return code (for example), but not ignore others to indicate that the install was a failure.