EC2 type of RHEL-Tower is not compatible with Ansible Tower 3.4

[davivcgarcia]

The environment created by aws_lab_setup playbook uses a `t2.medium' type for RHEL-Tower (control node). AWS creates instances with a little bit less than 4GB of memory, which is the minimum required by Ansible Tower 3.4.

When running the bundled installer, we see:

# ./setup.sh
(...)
TASK [preflight : Preflight check - Fail if this machine lacks sufficient RAM.] *****************************************************************************************
fatal: [localhost]: FAILED! => {"changed": false, "msg": "This machine does not have sufficient RAM to run Ansible Tower."}
	to retry, use: --limit @/home/student/ansible-tower-setup-3.4.3-1/install.retry

PLAY RECAP **************************************************************************************************************************************************************
localhost                  : ok=12   changed=1    unreachable=0    failed=1   

[error] Oops!  An error occurred while running setup.
[warn] /var/log/tower does not exist.
Setup log saved to setup.log.

Checking the instance memory:

# free -h
              total        used        free      shared  buff/cache   available
Mem:           3.5G        140M        1.2G         16M        2.1G        3.0G
Swap:            0B          0B          0B