go-zookeeper vendor package updated

Use updated architecture diagram

As much as we love @armon's omnigraffle, this new diagram better matches
the Vault branding 😄.

Enable audit-logging of seal and step-down commands.

This pulls the logical request building code into its own function so
that it's accessible from other HTTP handlers, then uses that with some
added logic to the Seal() and StepDown() commands to have meaningful
audit log entries.

Cubbyhole the world

Add sts:AssumeRole support to the AWS secret backend

Improved groups search for LDAP login

Minor grammar fix to vault vs custom solution comparison.

Use Consul API client's DefaultNonPooledTransport.

What we should probably do is create a client with a mutex and
invalidate it when parameters change rather than creating a client over
and over...that can be a TODO for later but for now this fix suffices.

Fixes #1428

aws-auth: naming of the locked and non-locked methods.

Rename lease_duration to refresh_interval when there is no lease ID, …

Rename lease_duration to refresh_interval when there is no lease ID, and output ---- between header and values

Add note about paid training