repl: Default `useGlobal` to false in CLI REPL.

Documentation for REPL states that the default value of `useGlobal` is
`false`. It makes no distinction between a REPL that is created
programmatically, and the one a user is dropped into on the command line
by executing `node` with no arguments. This change ensures that the CLI
REPL uses a default value of `false`.

Fixes: https://github.com/nodejs/node/issues/5659
Ref: https://github.com/nodejs/node/issues/6802


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
PR-URL: https://github.com/nodejs/node/pull/5703