changed number of installed servers from 2 to 3 (modified everything accordingly)
added some TF outputs for better user experience
added descriptions to all variables
removed install.sh script, and user data (ansible will take care of that)
added ansible-install.sh does the following:
-- writes playbook file
-- writes hosts file according to deployed instances
-- sleeps for 30 seconds (waiting for servers to be up)
-- installs ece (the desired version can be specified in variables.tf)