Update `ignore`, `debug`, other dependencies
Update `ignore`, `debug`, other dependencies

*   ignore@5.0.0
    <https://github.com/kaelzhang/node-ignore/blob/master/CHANGELOG.md>
    (likely breaking if using config files)
*   debug@4.0.0
    <https://github.com/visionmedia/debug/releases>
    (highly unlikely breaking)
*   concat-stream@2.0.0
    <https://github.com/maxogden/concat-stream/commits/master>
    (highly unlikely breaking)
*   to-vfile@5.0.0
    <https://github.com/vfile/to-vfile/releases>
    (highly unlikely breaking)

wooorm/unified-engine