Common interface for server security objects

Common interface for server security objects

Add an interface for creating arrays of server security objects.
This collects all of the various daemon code for initialising
security objects into one place, reducing duplication and making
it easier to add new objects in the future.

Change-Id: I9df20afccdbac4a610cb5bde32f01069272f27a2
Reviewed-on: http://gerrit.openafs.org/1177
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>