init commit.
add mongodb model.
support session.
add reg view
update resource.
add dependence[connect-mongo, connect, mongodb].
add model user.
update user reg interface.
update.
add dynamic helpers.
add login view.
add login logic judge.
add login logout control.
add hero-unit style to welcome block.
Merge branch 'feature/reg' into develop
add post model.
add post control
add user control
add posts/say view.
finish post