Factor common code to hyperdb/roundupdb There was some common copied code in backends/back_anydbm.py and backends/rdbms_common.py. This is now moved to hyperdb.py and roundupdb.py, respectively (the FileClass lives in hyperdb.py while the IssueClass is in roundupdb.py)

def audit_html_files(db, cl, nodeid, newvalues):
    if 'type' in newvalues and newvalues['type'] == 'text/html':
        newvalues['type'] = 'text/plain'
    

def init(db):
    db.file.audit('set', audit_html_files)
    db.file.audit('create', audit_html_files)