Libhoney

Improvements

- Default Transmission implementation now compresses payloads by default (using gzip compression level 1). Compression offers significant savings in network egress at the cost of some CPU. Can be disabled by overriding `transmission_impl` when calling `libhoney.init()` and specifying `gzip_enabled=False`. See our official [docs](https://docs.honeycomb.io/getting-data-in/python/sdk/#customizing-event-transmission) for more information about overriding the default transmission.

Fixes

- Switches default `send_frequency` type in the Tornado transmission implementation from float to timedelta, the correct type to use when fetching from tornado queues. Use of the float resulted in higher than expected CPU utilization. See [49](https://github.com/honeycombio/libhoney-py/pull/49) for more details.

Documentation updates only.

Improvements

- JSON encoder now defaults to string encoding of types not handled by the default encoder (such as datetime). Previously, these would result in a `TypeError` being raised during event serialization, causing the event to be dropped.

Security Updates

- Updates example Django app to 1.8.19 in response to [CVE-2017-7233](https://nvd.nist.gov/vuln/detail/CVE-2017-7233).

Improvements

- Adds default HTTP timeout of 10s. Previously, connections to the Honeycomb API would never timeout, blocking sending threads forever if communication or API service was disrupted.

Fixes

- Prevents rare RuntimeError leak during shutdown.