Use path.resolve instead of path.join to handle absolute paths.

`node -p 'p = require("path");p.join(".", "/a/b/c")'` gives us
`a/b/c`, but
`node -p 'p = require("path");p.resolve(".", "/a/b/c")'` gives us 
`/a/b/c`.

I think it's fairly clear that the second one is what you want in this case.  ;)