Fixing build process

[andreabenini]

the release.sh scripts fails on few things in my machine (linux AMD64)

• newer go version, 1.16.2 in my case. Fixed with bc,awk,sed to get all of them instead of relying on fixed if statements
• docker image name (previous was not available with docker pull)
• fixing path on work and source dir (so you can have your sources located everywhere)
• skip tests at will, still investigating why your tests don't pass on my linux machine. executable is fine and works btw... I reviewed the compile process because I'd like to contribute and add few things