update rspec tests for Git

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>
add rspec task

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>
finally rely on Minigit for Git operations

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>
add init? etc. functions and associated rspec

Signed-off-by: Sebastien Varrette <sebastien.varrette@uni.lu>