Use DataHandle in LoKi functors

Implemented functor SIZE which does almost the same as CONTAINS but uses new wrapper class LoKi::TES::DataHandle to declare data dependency.

There are some differences:

• SIZE can also get the size of every object on the TES implementing size().
• SIZE needs to be associated to a GaudiAlgorithm.
• RootInTES cannot be specified explicitly, this is taken from the associated algorithm.

The test requires gaudi/Gaudi!673 (merged) .