* test setup: ensure presence of /etc/protocols

* test setup: actually run secure_integration tests

When SECURE_INTEGRATION is speicified, the (non-secure) `:integration` specs
are excluded, so we cannot have the `:secure_integration` specs wrapped in a
context flagged as `:integration`.

* test setup: regnerate test certs (and add regen script)

* test setup: give ES the full cert chain

In order for the `ca_trusted_fingerprint` specs to work with the CA's
fingerprint, ES needs to be configured to present a cert chain that
includes the CA.

* resilience: prevent failures from crashing plugin

When an Event cannot be created directly from the hit, or when the
docinfo cannot be merged into a non-hash field in the hit, emit an
Event tagged with `_elasticsearch_input_failure` that contains the
JSON-encoded hit in `[event][original]` instead of crashing.

* add link to changelog

* remove orphan method from refactor