WIki - add info about gradle tasks to run for compiling VariaMos

[lufe089]

I'm submitting a...

[ ] Regression (a behavior that used to work and stopped working in a new release)
[ ] Bug report  
[ ] Feature request
[x ] Documentation issue or request
[ ] Improvement request
[ ] Support request => Please do not submit support request here

Current behavior

Building instructions to fix compilation errors and run variamos are missing in the wikidocs

Expected behavior

Complete the page "configuring the environment" inside the wiki to add how to compile an run unitary test on variamos by using gradle. Add images if necessary

[nherbaut]

@lufe089 instructions are windows only, do you need help with a linux version?