install.sh: Fix for Amazon's Linux AMI

Use /etc/os-release to determine distro

Contents of /etc/os-release on Amazon Linux AMI 2014.09:
NAME="Amazon Linux AMI"
VERSION="2014.09"
ID="amzn"
ID_LIKE="rhel fedora"
VERSION_ID="2014.09"
PRETTY_NAME="Amazon Linux AMI 2014.09"
ANSI_COLOR="0;33"
CPE_NAME="cpe:/o:amazon:linux:2014.09:ga"
HOME_URL="http://aws.amazon.com/amazon-linux-ami/"

Signed-off-by: Amit Bakshi <ambakshi@gmail.com>
Signed-off-by: Jessica Frazelle <jess@docker.com>

hack/install.sh

@@ -75,13 +75,23 @@ fi
 if [ -z "$lsb_dist" ] && [ -r /etc/fedora-release ]; then
 	lsb_dist='Fedora'
 fi
+if [ -z "$lsb_dist" ] && [ -r /etc/os-release ]; then
+	lsb_dist="$(. /etc/os-release && echo "$NAME" | cut -d' ' -f1)"
+fi
 
 case "$lsb_dist" in
-	Fedora)
-		(
-			set -x
-			$sh_c 'sleep 3; yum -y -q install docker-io'
-		)
+	Amazon|Fedora)
+		if [ "$lsb_dist" = 'Amazon' ]; then
+			(
+				set -x
+				$sh_c 'sleep 3; yum -y -q install docker'
+			)
+		else
+			(
+				set -x
+				$sh_c 'sleep 3; yum -y -q install docker-io'
+			)
+		fi
 		if command_exists docker && [ -e /var/run/docker.sock ]; then
 			(
 				set -x