This PR updates token revocation to use a non-recursive approach. On
very large trees this avoids stack overflows.

Fixes https://github.com/hashicorp/vault/issues/2348

Fixes #2334

* transit: change batch input format

* transit: no json-in-json for batch response

* docs: transit: update batch input format

* transit: fix tests after changing response format

* Update the help text for auditing headers

* Update help name

* Add /sys/config/audited-headers endpoint for configuring the headers that will be audited

* Remove some debug lines

* Add a persistant layer and refactor a bit

* update the api endpoints to be more restful

* Add comments and clean up a few functions

* Remove unneeded hash structure functionaility

* Fix existing tests

* Add tests

* Add test for Applying the header config

* Add Benchmark for the ApplyConfig method

* ResetTimer on the benchmark:

* Update the headers comment

* Add test for audit broker

* Use hyphens instead of camel case

* Add size paramater to the allocation of the result map

* Fix the tests for the audit broker

* PR feedback

* update the path and permissions on config/* paths

* Add docs file

* Fix TestSystemBackend_RootPaths test

* Transit: Support batch encryption

* Address review feedback

* Make the normal flow go through as a batch request

* Transit: Error out if encryption fails during batch processing

* Transit: Infer the 'derived' parameter based on 'context' being set

* Transit: Batch encryption doc updates

* Transit: Return a JSON string instead of []byte

* Transit: Add batch encryption tests

* Remove plaintext empty check

* Added tests for batch encryption, more coming..

* Added more batch encryption tests

* Check for base64 decoding of plaintext before encrypting

* Transit: Support batch decryption

* Transit: Added tests for batch decryption

* Transit: Doc update for batch decryption

* Transit: Sync the path-help and website docs for decrypt endpoint

* Add batch processing for rewrap

* transit: input validation for context

* transit: add rewrap batch option to docs

* Remove unnecessary variables from test

* transit: Added tests for rewrap use cases

* Address review feedback

* Address review feedback

* Address review feedback

* transit: move input checking out of critical path

* transit: allow empty plaintexts for batch encryption

* transit: use common structs for batch processing

* transit: avoid duplicate creation of structs; add omitempty to response structs

* transit: address review feedback

* transit: fix tests

* address review feedback

* transit: fix tests

* transit: rewrap encrypt user error should not error out

* transit: error out for internal errors

* awsec2: support periodic tokens

* awsec2: add api docs for 'period'

* approle: secret-id listing lock sanity

* Skip processing an empty secretIDHMAC item during the iteration

* approle: use dedicated lock for listing of secret-id-accessors

Ensure it's called on unmount, not just for seal.