modularizing server and introduce cli example.

Following up from https://github.com/GoogleCloudPlatform/google-cloud-datastore/pull/50, this sent the server files to a new `/server` directory, as well as introduced a CLI example a little more sophisticated than the one from the earlier PR.

An easier to look at representation: https://github.com/stephenplusplus/gcloud-node-todos

![screen shot 2014-09-26 at 3 13 33 pm](https://cloud.githubusercontent.com/assets/723048/4426388/08dfd2ca-45b3-11e4-9f7b-b95a6b08d8e1.png)
:+1: although this might be uncovering some underlying confusion I'm having. I don't consider the server an app, rather the gcloud integration point, simply always running in the background for the FE implementations to ping.

It does make sense to move it out of `server/` just to make it more visible from the frontpage.