Iobeam

- **IMPORTANT**: The client now correctly tracks batches it has seen before
so subsequent calls to `send()` do not send nothing.
- Documentation fixes

- Adding data should now be done via the new `iobeam.createDataStore(columns)` method,
which allows you to track multiple streams of data in one object.
- Internally, old methods involving `DataPoint`s and `DataSerie`s have been converted
to use `DataStore`s.
- Additional documentation provided [here](https://github.com/iobeam/iobeam-client-python/blob/master/docs/DataGuide.md).

- Automatic refresh of project tokens when they are expired. It is recommended that you
update as soon as possible to avoid breakage.
- bugfix: device ids are no longer allowed to be non-strings when registering

- **IMPORTANT**: previously sent data points were being kept and sent on subsequent sends, this
has been fixed
- Query assumes time values given in to/from are same unit as when it is initialized

- `Timestamp`: changed `type` param name to `unit` in constructor
- utils: Adds a check for whether this is python2 or 3
- New Error for duplicate ids
- New `registerOrSetId()` added to `iobeam.ClientBuilder` to allow you to register a name, or
if it already exists, set the client to use that id.

- Fix missing return for `iobeam.makeQuery()`