* Use SHA2-256 hash with prefix to upgrade the paths
* test the SHA1 upgrade to SHA256
* Remove hash identifier and the delimiter; use 's' instead
* Added API test to verify the correctness of the fix
* Fix broken test
* remove unneeded test
* Start work on passing context to backends
* More work on passing context
* Unindent logical system
* Unindent token store
* Unindent passthrough
* Unindent cubbyhole
* Fix tests
* use requestContext in rollback and expiration managers
This commit splits ACL policies into more fine-grained capabilities.
This both drastically simplifies the checking code and makes it possible
to support needed workflows that are not possible with the previous
method. It is backwards compatible; policies containing a "policy"
string are simply converted to a set of capabilities matching previous
behavior.
Fixes#724 (and others).
