Github user FlorianHockmann commented on the issue:
https://github.com/apache/tinkerpop/pull/867
Turns out that it was very easy to add a check if mono is present and
otherwise skip the package of the template:
```xml
<if>
<available file="mono" filepath="${env.PATH}"/>
```
I rebased and squashed the commits as I had to revert changes I made to the
dev docs because mono now isn't required any more to build the `gremlin-dotnet`
module.---
