Update Babel version number to latest 5.x
Update Babel version number to latest 5.x

At the moment Babel 5.8.34 is going to be installed anyway if you
install lebab, so better to be explicit about this and not concern
ourselves with supporting older Babel.

But not upgrading to Babel 6.x as it does contain some major changes.

mohebifar/lebab,mohebifar/xto6,lebab/lebab