temp commit

remove "import random" which is not used any more
version alpha 0.3.0

changes:
1.change message saving mode, save one copy for a unique conversation,
  save all chat messages in one day to a single file

new:
1.add test mode to MessageSaver to reduce the writing_interval;
2.add web server logic in views, and tests

bugs:
1.test_clients won't exit automatically after execution, reason not clear.