Computer Janitor
Computer Janitor is being dropped in the next version of Ubuntu - mainly because nobody used it and the serious perceived issues that it could break your system with some of its suggestions.
I would recommend you take a closer look at either Ubuntu Tweak (from here) or Bleachbit (from software centre)
There is an AU question here with regards to Ubuntu Tweak.
I haven't found a similar question for BleachBit - but this AU question may help.