info.Validate is called twice

[erikgeiser]

Currently info.Validate is called twice, once after parsing the config and once in each packager. Unfortunately this is somewhat costly for large packages due to file stat'ing and sorting.

We could either remove one of the calls or add an internal variable to keep track if it was already called and make it a no-op in this case.

If we decide on a solution I can add it to #388 as it is kind of related.

[djgilcrease]

I would leave only the one in the packagers