impl: ORM Model
port to useing  SQLAlchemy; remove the concept of stack; allow append new todo to the bottom of list
Sat Feb 22 17:23:44 CST 2014
Sat Feb 22 17:35:56 CST 2014
Sun Feb 23 08:50:15 CST 2014
Sun Feb 23 10:10:36 CST 2014
Sun Feb 23 11:30:22 CST 2014 fix: append
add bootstrap
Sun Feb 23 17:38:25 CST 2014
perfect ui
udpate requirement.txt