add title
add tag column. add shared/header file
add shared/_messages.html.erb file
add shared/_footer.html.erb file
add messages form. modify foundation_and_overrides.scss file
add submit message form
update
Merge branch 'add_message'

Conflicts:
	app/assets/stylesheets/foundation_and_overrides.scss
	app/views/main/index.html.erb
add tag model, message model. Modify the main page to messages#index
add delete function. modify the show function.
create or delete tags && messages. add message multiple to tag multiple relation. add tag_index column to tag table
remove index from tag table. add remove dupliate function under tag model.
click each tag, got the different kinds of messages
add user sign-up/login and logout feature.
add relationship between user and message
add 'pg' gem, and unicorn gem
add unicorn.rb file
change the 'log' to 'logs'.
change the 'log' menu under the application 'log' menu.
change 'log' to 'logs'.