Added skeleton models for GradingSurveyGroup and Records. SurveyRecordGroup has been renamed to GradingRecord. GradingSurveyGroup will hold which Surveys should be linked. While the acompanying GradingRecords (with their reference to a GradingSurveyGroup) will hold the Records for each StudentProject that can take these Surveys.

"""
Code used in a couple of places to work with the current thread's environment.
Current users include i18n and request prefix handling.
"""

try:
    import threading
    currentThread = threading.currentThread
except ImportError:
    def currentThread():
        return "no threading"