Refactor api

Here are some of my ideas around refactoring how InfluxDB's API works. The key learning here is that people have been using string columns like tags and it leads to bad performance.

My goal here is to make that the default and to expose an API that is more purpose built around the metrics/time series use case as opposed to the more general purpose SQL.

Please comment on the individual lines of [influx_api_v2.md](https://github.com/influxdb/influxdb/blob/refactor-api/influx_api_v2.md) for focused feedback. Or leave comments in the thread for more general thoughts.

I'm also very interested in hearing about specific use cases. Have I captured everything here? What have I left out? I know this can't encompass everything, but my hope is that it creates a clean foundation that we can easily expand upon.

@jvshahid, @toddboom, @benbjohnson, @dgnorton, @otoolep: please to review.
Just as a point of reference, collectd can and depending on the metric does store multiple values. Ie for network traffic, received and transmitted are stored in the same series. Similar with disk reads and writes.

(I'm not implying that influxdb should or shouldn't allow this, just putting it out there for comparison)