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

@@ -34,7 +34,7 @@
         "@types/shelljs": "0.7.8",
         "mocha": "^3.5.3",
         "nock": "9.6.1",
-        "shelljs": "0.7.8",
+        "shelljs": "0.8.5",
         "typescript": "3.1.5",
         "@types/node": "8.9.2"
     }