User should be aware that this project requires Bash 4

[legovaer]

I'm currently using OS X El Capitan Version 10.11.2 which is using GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin15) by default.

As we are using declare -A in scripts/build_all.sh, the user should be aware that he/she needs to update bash to a version which is higher as 4.

Two suggestions;

• Add this requirement to README.md
• The script will check the version of bash and displays an error when an old version is used

[ricardoamaro]

This is a testing version of Drupal testbot using docker containers, main url is: https://drupal.org/project/drupalci_testbot

Cheers!