如何在不同版本的Julia之间切换（特别是在Ubuntu上的v0.3和v0.4之间）？

I am working on some projects using Julia v0.3. However, I'd like to test my code in both v0.3 and v0.4 (since some of the people that are going to be using it are already using v0.4). I'm running Ubuntu 14.04 and have installed Julia using apt-get. I know v0.4 is available through the PPA julianightlies, but if I add this, v0.3 is replaced. Is there a way I can install and quickly switch between both versions for testing purposes?I am working on some projects using Julia v0.3.