fix breakage in problem checker caused by LoncapaProblem taking a file object in…

fix breakage in problem checker caused by LoncapaProblem taking a file object in its constructor instead of a filename

common/lib/capa/capa_problem.py

@@ -127,7 +127,7 @@ class LoncapaProblem(object):
             responder.preprocess_response()
 
     def __unicode__(self):
-        return u"LoncapaProblem ({0})".format(os.path.basename(self.filename))
+        return u"LoncapaProblem ({0})".format(os.path.basename(self.fileobject.name))
 
     def get_state(self):
         ''' Stored per-user session data neeeded to: 

common/lib/capa/checker.py

@@ -32,7 +32,7 @@ def main():
         log.info("Opening {0}".format(problem_file.name))
 
         try:
-            problem = LoncapaProblem(problem_file.name, "fakeid", seed=args.seed)
+            problem = LoncapaProblem(problem_file, "fakeid", seed=args.seed)
         except Exception as ex:
             log.error("Could not parse file {0}".format(problem_file.name))
             log.exception(ex)