Suffixes not allowed for docker-compose.yml

[tiffanyfay]

Created to address aws/amazon-ecs-cli#1

docker-compose.yml

web:
    image: nginx
    ports: 
        - "80:80"
    mem_limit: 50M

ERRO[0000] Failed to unmarshall: strconv.ParseInt: parsing "50M": invalid syntax
web:
  image: nginx
  mem_limit: 50M
  ports:
  - 80:80

Fix:
Change

intType, err := strconv.ParseInt(stringType, 10, 64)

to

if stringType == "" {
	return errors.New("Unmarshalled string is empty. Failed to convert to IntType")
}
intType, err := units.RAMInBytes(stringType