Added gem console.
Added gem console.

Resolves Bundler deprecation warnings with Bundler 2.1.x:

    [DEPRECATED] bundle console will be replaced by `bin/console`
    generated by `bundle gem <name>`

Use of `bundler console` is now deprecated and replaced with
`bin/console` which mimics `bundle gem <name>` behavior.

bkuhlmann/tokener,bkuhlmann/tokener,bkuhlmann/tokener