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.
"Each series has a single value...."

Can you clarify this statement? I want to be sure I understand the terminology here. A series is something like:

cpu.host1.idle

and it may have many, many timestamp meaurements. I think of each of these as "values". Perhaps when you mean "value" you mean that the data "schema" is that there is one value for this metric, at a given point in time i.e. it's not a 2-dimensional value. Is that what you mean?