Limit heap usage to 128mb

[jroper]

By default, Java will use a max heap size of 25% of the available system memory. So, let's say you're using n1-standard-4 compute nodes on GCE, system memory available to a container without setting any resource limets will be 15GB, so it's going to default to almost 4GB heaps, about 32x what this app really needs.