Upgraded Kubernetes to 1.7.3 and Calico to 2.4.1

[rbjorklin]

• Tested & working with CoreOS Alpha 1506.0.0
• Upgraded Kubernetes from 1.5.4 to 1.7.3
• Upgraded Calico from 0.23.0 to 2.4.1
• Upgraded kube-dns from 1.9 to 1.14.4
• Upgraded dns-autoscaler from 1.0.0 to 1.1.2
• Upgraded heapster from 1.2.0 to 1.4.1
• Upgraded kube-dashboard from 1.5.0 to 1.6.3
• Changed from using etcd2 to etcd version 3
• Changed Calico to the default network solution
• Changed POD_NETWORK from 10.2.0.0/16 to 192.168.0.0/16 as Calico does not respect CALICO_IPV4POOL_CIDR
• Changed Vagrant memory limits for the controller, increased to 2Gb
• Removed Kubelet usage of deprecated flag --api-servers
• Removed Kubelet usage of deprecated flag --register-schedulable
• Added a kubeconfig to make up for the removed flags above
• Added possibility to modify how many cpu cores Vagrant assigns the hosts

[tmjd]

I'm glad to see the whole guide updated. Partially addresses #899

@rbjorklin Were you going to revert the change to the CIDR. We talked on the CalicoUsers slack and I think you understand CALICO_IPV4POOL_CIDR better now, do you still believe it is not respected?