Added support for Amazon Linux startup script

Script is based heavily off of the CentOS/Redhat script, with the calls to super removed.

I'm not quite sure how to test this apart from firing up an EC2 instance with the Amazon Linux AMI, but if you have any suggestions, I'm more than willing to implement them.

For what it's worth, my installation process looks like this (starting from fresh Amazon Linux):

```
# Update
sudo yum update
sudo yum groupinstall "Development Tools"

# Set up Node.js
curl https://raw.github.com/creationix/nvm/master/install.sh | sh
source ~/.bash_profile
nvm install 0.10 && nvm use 0.10 && nvm alias default 0.10
```