add 2 divs and change 1 block name

1. add page and content div
2. change block  'main-page' to block 'article'
create class forms in forms.py
move forms.py to folder contact
edit contactus
edit class ContactForm
edit base.html
edit contactus in urls.py
fixed some errors

1. fix some syntax errors
2. fix 'no module for contact.forms': add __init__.py in contact folder
repair some hyperlinks
fix an action attr
fix 3 labels
fix some uncomfortable places