[cs615asa] setting up amazon ec2 cli tool

[nbevacqu]

I finally figured out how we can set up the ec2 cli tool. Part of the 
confusion was that there are several different tools (all named *aws* in 
some fashion) and tutorials online don't tend to specify which one they 
are using. The following works with the aws executable installed under 
/usr/local/bin/aws

First, create a text file with the following content:

[default]
aws_access_key_id = <access key id>
aws_secret_access_key = <secret access key>
region = <ec2 region>

<access key id> and <secret access key> are from the key you create on 
the security credentials page under the Amazon ec2 settings.
<ec2 region> is any valid ec2 region such as us-east-1.

Then, set the AWS_CONFIG_FILE environment variable to be the path to 
that file.

With that set up, you should be able to run commands like `aws ec2 
describe-regions`.

I hope that helps everyone get started.

Sincerely,
Nicholas Bevacqua