Make rejected photos aren't computed in user's stats

[nilovelez]

Currently, both submissions errors like theese:
https://meta.trac.wordpress.org/ticket/7565

...and photos moderators reject as "Error: submission error" are counted while computing user stats. This seems unfair for users and might give moderators a wrong impression while evaluating a user.

I think both of this cases should be excluded from stats, and maybe others