Ticket 47635: MT/Backend/Suffix to be conform with the design
    
    Bug Description:
    	This bug is to create MappingTree/Suffix classes and to move Backend from brooker.py
    	to a dedicated file.
    	Then to implement the interface of each classes as described in http://port389.org/wiki/Upstream_test_framework
    
    Fix Description:
    
    	Implements:
    
    		Mapping Tree:
    			mappingTree.py: MappingTree/list-create-delete-getProperties-setProperties-toSuffix
    			mappingTree_test.py: unit tests
    		Backend:
    			brooker.py: remove Backend from that file
    			backend.py: Backend/list-delete-create-getProperties-setProperties-toSuffix
    			make readonly local function that will be reimplemented with setProperties
    			backend_test.py
    			suppress/replace methods implemented in others classes
    			  setupBackend/getSuffixForBackend
    		Suffix:
    			suffix.py:Suffix/list-toBackend-getParent
    			suffix_test.py: unit tests
    			suppress/replace methods implemented in others classes
    			  getSuffixes/setupSuffix/getBackendsForSuffix/findParentSuffix/addSuffix
    
    			  getSuffixes/setupBackend/setupSuffix/getBackendsForSuffix/getSuffixForBackend/findParentSuffix/addSuffix
    
    https://fedorahosted.org/389/ticket/47635
    
    Reviewed by: Rich Megginson
    
    Platforms tested: F17
    
    Flag Day: no
    
    Doc impact: no