Adjust kube-up.sh to accept command line options.

In preparation for making other changes I thought I would propose an initial change to kube-up.sh to process command line options. Added are options for help and for specifying logging with fluentd and Elasticsearch and fluentd with GCP.
Command-line arguments are not the way to go here. We use environment variables to configure everything. I don't see a reason to diverge from that pattern. 

Another reason to not use command-line flags is that they require more plumbing. Search for `kube-up.sh`. It's invoked from `hack/dev-build-and-up.sh`. Are you going to add command-line args to that script? How about to `icebox/cluster/rackspace/kube-up.sh `? `hack/e2e-test.sh`? 

Just take KUBE_FLUENTD_ELASTICSEARCH and KUBE_FLUENTD_GCP from the environment.