Use Heapster as an in-built monitoring solution for Kubernetes in GCE.
Users will have an option to enable it when they setup their cluster (kube-up).
Add an option for enabling monitoring in gce/config-default.sh and disable it
for tests.
Updated heapster readme.
Improve the monitoring setup script and fix bugs in the monitoring config.
Merge pull request #2208 from vishh/monitoring

Use Heapster as an in-built monitoring solution for Kubernetes in GCE.