add GPLv3 mention in teh README

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>
Minor bump to version 0.4.0-b34

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>
Merge branch 'release/0.4.0-b34'

* release/0.4.0-b34:
  Minor bump to version 0.4.0-b34