If you want to go the yocto package route, nano is include as part of the openembedded/meta-oe yocto layer. Instructions for adding the meta-oe layer to your yocto build environment are included in the doc located here: Edison BSP User Guide_331188-001.pdf
You can basically for the instructions for "Add third-party packages to the image" and replace IMAGE_INSTALL += "opencv" with IMAGE_INSTALL += "nano"
