bump to version '0.2.11'

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>
Update Gemfile.lock accordingly

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>
Merge branch 'release/0.2.11' into devel

* release/0.2.11:
  Update Gemfile.lock accordingly
  bump to version '0.2.11'