I seem to always add little posts about trivial things that messed me up.
Android studio 1.0.2 – couldn’t work out how to access the libs dir to add a jar file from another project I have.
So simply copy it by hand into the libs directory (under app – same level as src).
Then in Android Studio there is a little dropdown on the left hand top side of the project window. By default it says Android with a little droid symbol. Click on it and you get other options. Select “Project” and you can now see all the directories and can right click your library and “add as library”. It even does the gradle integration for you.