msbuild task fails to revolve msbuild in linux because first tries to find mono`

[lmendez-pros]

I tested the plugin on an GoCD agent with Net framework installed and the plugin seems to fail to resolve the location because it first tries to find mono binary location and since it's not installed it fails right away without even trying to find the msbuild.dll.

executing which mono command at the beginning is causing the plugin to fail without looking for other possible locations to run msbuild.

If mono is not installed the code should still try to find msbuild from other locations implemented in the code.