* govet cleanup in token store
* adding general ttl handling to login requests
* consolidating TTL calculation to system view
* deprecate LeaseExtend
* deprecate LeaseExtend
* set the increment to the correct value
* move calculateTTL out of SystemView
* remove unused value
* add back clearing of lease id
* implement core ttl in some backends
* removing increment and issue time from lease options
* adding ttl tests, fixing some compile issue
* adding ttl tests
* fixing some explicit max TTL logic
* fixing up some tests
* removing unneeded test
* off by one errors...
* adding back some logic for bc
* adding period to return on renewal
* tweaking max ttl capping slightly
* use the appropriate precision for ttl calculation
* deprecate proto fields instead of delete
* addressing feedback
* moving TTL handling for backends to core
* mongo is a secret backend not auth
* adding estimated ttl for backends that also manage the expiration time
* set the estimate values before calling the renew request
* moving calculate TTL to framework, revert removal of increment and issue time from logical
* minor edits
* addressing feedback
* address more feedback
* 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
1) Use the new LeaseExtend
2) Use default values controlled by mount tuning/system defaults instead
of a random hard coded value
3) Remove grace periods
Currently permissions are not revoked, which can lead revocation to not
actually work properly. This attempts to revoke all permissions and only
then drop the role.
Fixes issue #699
