Implemented local default config file

With this change, if `eslint` is run without specifying a config file,
a search will be performed for an `eslint.json` config file.

The search will begin in the current working directory, and recurse
upwards until the filesystem root is reached.

If no `eslist.json` file is found, then the default `eslint.json` in the
eslint application directory will be used.