maildir.lua fix

Hi I've made a few fixes in both the maildir.lua and util/init.lua files. For the first one, it was crashing while dispalying mails' count due to a missing function in  util/init.lua file. 
Additionally, I've included a global variable which counts the total number of email and removed the local count variable which was not used at all. 

Thanks & Regards,
TLux