Okay ladies and gentlemen ... It appears that thanks to the hard works of @Fif7y , @codedit , and @imrel0ad , we now have ThemeIt (Ti) working again on 5.0-5.1.1
It's been a battle to get it situated and running properly but the guys made it happen. You may now go and download all your favorite themes from Ti again.
Oh yeah, with ThemeIt ready, that means the highly anticipated theme, boss.ios by @fif7y and the G-team will be available soon. Expect to see it arriving within the next few days!!!
You may add the following repo in Cydia to get ThemeIt