Use #!/bin/sh instead of #!/bin/bash when possible

[emanuelb]

Description

Several scripts in this repo use #!/bin/bash when it's not needed and #!/bin/sh can be used instead (thus not require the bash dependency) for example in buildCheckpoints.sh file the change is possible, for other files it's require testing, the checkbashisms tool might help for testing: https://manpages.debian.org/jessie/devscripts/checkbashisms.1.en.html