Comment 16 for bug 556829

Created an attachment (id=435225)
less hacky but more complicated fix

This change makes it so the current STATUS operation doesn't have its folder in m_foldersToStat, which means we have to check if there are any folders left before doing the next stat. It also means we won't be potentially removing the wrong folder when the STATUS operation finishes. And I put some code to prevent us from putting the same folder in the array multiple times, which should ameliorate the case of the user hitting get new mail twice.