define kernelpath for clientside notebook manager

Otherwise starting the kernel choke on google drive path that are not localhost path.

I'm wondering if we should not make that the default behavior of `ContentsManager` instead of return `path`, 
or just verify that cwd is a dir in launch kernel or earlier. 
I can have a look. Though now I really need to finish correcting my dissertation before coming to the US.
If you got time please go ahead.