Renamed the setName/GetName functions to the more appropriate getAddress/setAddress.

Created a richer protocol buffer RootEntry object and created a parital implementation to allow unit tests to run.

middletier, itself separated in interface, SQLite, objectstore and
shared tests.
Moved all utilities (exceptions, threading...) to a shared utility
directory.
Created a single, shared unit test from all the scattered ones.

Used exceptions while moving Vfs to creating its temporary directory using mkdtemp. This allows several Vfs intances to run on the same
system simultaneously.
Updated the model of the abstract unit test so it can instanciate one test environement per unit test. This was needed in the current
unit test for middle tier admin.

Created AdminUsersList in the object store as a first step to implement an object store middle tier.
Some namespace fixes for unit tests.

and created initial unit tests for those.

Intermediate commit: factored the base operations on ObjectOps and started to apply them to RootObject.

Implemented the new interface on the Rados backend.
Fixed several bugs.

The context handle concept is being dropped, with scoped lock objects in place.
The VFS backent store now compiles.

Intermediate commit: started to implement the garbage collection, plus a producer and consumer action.
The Agent class is becomming too complex, so started to split it up between the current agent (living with the application it represents)
and the AgentVisitor, which will look at it from the outside (for the garbage collector).

The intent log exists in the root entry only for the agent register creation. Then the agent register has an agent creation intent log
as well. And finally for all other usages, the agent's intent log shall be used.

This is a working compilation checkpoint. Some intent logs still need to be removed from the schema.

Some legacy utilities from castor were imported alongside, with some adaptations.