Shared Objects.

Shared Objects.

This commit introduces shared objects. The implementation is fully
resource manager independent, and thus can be used with dummy, AQuoSA,
CGroups, or whatever else.

A small uncompliance with the FRSH API semantic is present, since we
need the user not to create an external mutex that will be associated
with the shared object. Instead, we create the mutex along with the
shared object and return it to the user together with the shared object
handle.
This issue will be further analyzed to find out if it would be possible
to remove it...

Moreover, this commit does not fully implemente serialization and
deserialization for the critical sections contract block, since more
discussion is needed to address the issue. Thus, we only provide some
stubs here, just to make the framework compile and run some simple
tests.

Signed-off-by: Michal Sojka <sojkam1@fel.cvut.cz>