Port functions from terraform-aws-zookeeper (gruntwork-io#37)

* Define string_substr function

* Add function that asserts whether the user has permissions to run sudo

* Add " for consistency

Fix build (gruntwork-io#36)

* Regression test for sudo functionality

* Add Ubuntu 20.04 and propagate exit code

* Fix for sudo bug

* Fix build failures

* Make sure shellcheck container errors are bubbled up

* Remove debug statement

* Fix docker-compose call for shellcheck

Add ability to run user mod commands with sudo (gruntwork-io#35)

Addition of function to calculate rally point instance in AWS Auto Sc…

…aling Groups (gruntwork-io#33)

* Dockerfiles have been updated to use Python 3 due to multiple issues with running under Python 2.

* A new function, aws_wrapper_get_asg_rally_point, has been added. This allows you to calculate a single 'rally point' instance that is part of an auto-scaling group, useful for executing bootstrapping commands once per ASG.

* Refactored new unit tests to include a custom setup function for each set, and split out public vs private hostname call scenarios to be consistent with other tests.

* The Dockerfiles for tests have been updated to include setting some encoding environment variables, which resolves some issues when running tests, as well as removing some un-necessary 'sudo' calls.

* Steps to install some new dependencies have been moved to the 'Install basic dependencies' section of the test Dockerfiles per comments from maintainer.

* The comment for the new function has been updated per maintainer comment.

* Variable usage and whitespace have been updated per comments from the maintainer.

* Additional tests have been added for the 'aws_wrapper_get_asg_rally_point' function to ensure that the function fails when the ASG does not contain the requisite number of instances after the given retry / wait period has elapsed.

* The Dockerfiles for the tests have been updated to include better comments / details around the use of the locale environment variables.

Merge pull request #4 from gruntwork-io/dynamic-ubuntu-waiter

Added new dynamic-ubuntu-wait.sh

Merge pull request gruntwork-io#15 from jeckhart/minor-fix-for-bootst…

…rap-compat

Minor fix for bootstrap compat

Merge pull request gruntwork-io#14 from jeckhart/add-commons-commands…

…-from-zk-and-kafka

Add commons commands from package-zookeeper and package-kafka

Merge pull request gruntwork-io#11 from housni/feature/portability-ad…

…ditions

Portability additions

Merge pull request gruntwork-io#10 from gruntwork-io/feature/file-fil…

…l-template

Add function to fill out template strings in files

Merge pull request #7 from gruntwork-io/tag-pending-running

Filter pending and running