Fix MySQL availability tries counter (#150)
Fix MySQL availability tries counter (#150)

The variable `i` was not declared and never incremented.
ajvpot/CTFd,liam-middlebrook/CTFd,CTFd/CTFd,gibsonnathan/CTFd,LosFuzzys/CTFd,liam-middlebrook/CTFd,ajvpot/CTFd,isislab/CTFd,gibsonnathan/CTFd,gibsonnathan/CTFd,LosFuzzys/CTFd,CTFd/CTFd,CTFd/CTFd,jaboyles/CFTD_Senior_Project,mschwager/CTFd,ajvpot/CTFd,CTFd/CTFd,isislab/CTFd,LosFuzzys/CTFd,mschwager/CTFd,liam-middlebrook/CTFd,mschwager/CTFd,ajvpot/CTFd,isislab/CTFd,LosFuzzys/CTFd,gibsonnathan/CTFd,isislab/CTFd,liam-middlebrook/CTFd,jaboyles/CFTD_Senior_Project,jaboyles/CFTD_Senior_Project,mschwager/CTFd,jaboyles/CFTD_Senior_Project