Create a Properties class based on the Gaudi PropertyWithValue implementation

[NickDraper]

Create a Properties class based on the Gaudi PropertyWithValue implementation
Look at GAUDI http://proj-gaudi.web.cern.ch/proj-gaudi/releases/v19r3/doxygen/class_property_with_value.html

The property class should include the following methos (many more may be taken from GAUDI)
- string name; //the property name
- `` operator=(),//to return the value (we should support int double and string as a minimum)
- `` operator= ( const TYPE & value ) //to set the value
- bool isDefault(); // if the value held has been set by the default value of the class
- bool isValid(); // true if the property has a valid value.

[NickDraper]

This issue was originally trac ticket 54