Removed unused and stylistically incorrect class defs

common/djangoapps/models/course_relative.py

-class CourseRelativeMember(object):
-    def __init__(self, location, idx):
-        self.course_location = location     # a Location obj
-        self.idx = idx                   # which milestone this represents. Hopefully persisted # so we don't have race conditions
-    
-### ??? If 2+ courses use the same textbook or other asset, should they point to the same db record?        
-class linked_asset(CourseRelativeMember):
-    """
-    Something uploaded to our asset lib which has a name/label and location. Here it's tracked by course and index, but
-    we could replace the label/url w/ a pointer to a real asset and keep the join info here.
-    """
-    def __init__(self, location, idx):
-        CourseRelativeMember.__init__(self, location, idx)
-        self.label = ""
-        self.url = None
-        
-class summary_detail_pair(CourseRelativeMember):
-    """
-    A short text with an arbitrary html descriptor used for paired label - details elements.
-    """
-    def __init__(self, location, idx):
-        CourseRelativeMember.__init__(self, location, idx)
-        self.summary = ""
-        self.detail = ""
-        
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