重构Models结构
Update scriptfan root module
Remove extensions package
Move scriptfan.utils.filters to scriptfan.filters
Rename activity.py view to events.py view
refactor file structs
重命名 activity 相关变量为 event
Create EventDuration Model (Sync with database)
Fix errors for events url mapping
Improve event creation form

1. Separate duration date, start_time and end_time
2. Set default values for duration
Fix mysql chinese characters errors

1. Add notes in readme to create database with collation: utf8
2. Fix url error in user signin and signup form.
3. Update scriptfan and alebic conig file database url
Update event creation.
Merge pull request #13 from ScriptFan/refactor_events

Refactor events