WIP: Implement writes series data on database

Not ready yet, just opening a PR to start some discussion.

The interface for interacting with the metastore feels clunky on my first pass trying to use it. I almost feel like there needs to be another abstraction over those transactions.

For example, this spot https://github.com/influxdb/influxdb/compare/write_series?expand=1#diff-320bbef96d874515320f176727a55ea8R410 where I have to close over the variables and set them feels really off.

Thoughts @benbjohnson?
A couple notes on this function:

* I think we should keep series in-memory so we don't need to open a view transaction on every read.
* Go convention is to drop "get" from getters so it'd be `seriesId()`.
* Go convention is also to [use `ID` instead of `Id`](https://code.google.com/p/go-wiki/wiki/CodeReviewComments#Initialisms) so it would actually be `seriesID()`.

Part of the reason the getter feels clunky is that it's just wrapping the `metatx`. If you want your metastore calls to be transactional then you should wrap the caller of `tx.seriesID()` in a transaction. Also, getters typically don't need errors returned in bolt. In this function the `bool` is redudent because `uint32(0)` implies that it's not found.