`path.exists*` functions show a deprecation warning and call functions
from `fs`. They should be removed later.
test: fix references to `path.exists*` in tests
test fs: add test for `fs.exists` and `fs.existsSync`
doc: reflect moving `path.exists*` to `fs`
With -e or --eval, require() can load module using relative path.
node -e 'require("./foo")'
But it can't load module from node_modules directory.
node -e 'require("foo")'
Fixes#1196.