PrioDir: Fixed event handler
doc: minor fixes
Revert "doc: minor fixes"

Commit had more stuff in it than it should have.

This reverts commit a9a7c84703eb7250012fd68af3e4ca77eae07029.
doc: minor fixes
Metadata: group_in_category fixes

Moved ClientMetadata.group_in_category to
MetadataQuery.group_in_category, with a deprecation warning for the
old place.  Also changed the null answer (i.e., this client isn't in a
group in that category) to None from ''.
Rewrote arbitrary data cache system

The caching facilities in Bcfg2.Server.Cache provided basically no
features.  This rewrites that to allow for much more powerful cache
expiration, with a particular focus on interoperation between
different components and plugins to let caches be expired as
necessary.  (E.g., the Probes plugin can expire the Metadata cache.)

This does not affect any of the file data cached by Bcfg2, only the
caches that are populated with arbitrary data (Metadata, Packages,
Probes, etc.).
Options: fixed error message when bcfg2.conf is not readable
Probes: rewrite for new caching system

Substantially rewrote the way the Probes plugin caches data.
Formerly, it was structured to assume that probe data was stored in
probed.xml, with the database feature very much a second-class
citizen; this adds a proper abstraction layer between the persistent
storage and the plugin (and its caches).

Also rewrote most Probes unit tests to actually be useful unit tests,
not implementation tests.
Revert "Metadata: group_in_category fixes"

This reverts commit 35498c8b849c15632d720656d5736c4c85f76b53.

group_in_category() access data that's held on the ClientMetadata
object, and getting that data via the MetadataQuery object would be
more expensive.
Encryption: minor fixes
Core: Added default ACLs

Since we're exposing more stuff via XML-RPC, this adds a default,
fairly restrictive ACL plugin if no other ClientACLs plugin is loaded.
This makes us secure by default.