Bump shelljs from 0.7.8 to 0.8.5

Bumps [shelljs](https://github.com/shelljs/shelljs) from 0.7.8 to 0.8.5.
- [Release notes](https://github.com/shelljs/shelljs/releases)
- [Changelog](https://github.com/shelljs/shelljs/blob/master/CHANGELOG.md)
- [Commits](shelljs/shelljs@v0.7.8...v0.8.5)

---
updated-dependencies:
- dependency-name: shelljs
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

package-lock.json

@@ -96,7 +96,7 @@
     "prettyjson": "^1.1.3",
     "requirejs": "^2.2.0",
     "rimraf": "^2.5.4",
-    "shelljs": "^0.7.6",
+    "shelljs": "^0.8.5",
     "style-loader": "^0.18.2",
     "uglify-js": "^3.4.5",
     "webpack": "^3.5.4",