Add a basic script to compare the db_schema to the fs_schema.
Allow SchemaViewer to be used without a request object Most use of self.req have
been hidden in method that fallback on a simple behaviour when no req are
provided.
Several element have been sorted to ease comparison.
if versions_map['cubicweb'][0] == (3, 7, 4):
config['http-session-time'] *= 60
config['cleanup-session-time'] *= 60
config['cleanup-anonymous-session-time'] *= 60