Extraneous slash in feature path causes failure

An extra slash in the path to the feature file causes relative features to not be found.

This fails due to the double slashes between `commission` and `posting`.
```
mvn clean test '-Dkarate.options=classpath:commission//posting/fields.feature'
```

Without the double slashes, it works as expected.
```
mvn clean test '-Dkarate.options=classpath:commission/posting/fields.feature'
```