Error: "app.match is not a function" when --app begins with "-"

Example reproduction:

```bash
$ mobile-center test run uitest --app "-a-/app" \
   --devices 12345678 --app-path MyDrivingiOS.ipa \
   --test-series "master" --locale "en_US" \
   --build-dir  MyDriving/MyDriving.UITests/bin/Debug \
   --uitest-tools-dir packages/Xamarin.UITest.2.1.3/tools
Preparing tests... done.
Error: app.match is not a function
```
