[IMP] sale,warning: usability
[IMP] ir_qweb: remove the option 'only_date' introducted in cefc9ad8e3e3b0a14804da6c40bfd71e16d4175a. Now we can use widget='date' to do the same thing. That keeps the same behaviour that in the backend.

    <span t-field=model.datetime_field t-field-options="{'widget': 'date'}"/>
[FIX] perview button visible
[IMP]website_blog: change gallery view of blog post and add option into customize menu, also implement customize grid and promote blog using sequence.
[IMP]Improved code.
[IMP]website_blog:some change in js and css.
[IMP]improved code.
[IMP]Improved Code.
[IMP]website_blog:some change in js and css.
[IMP]website_blog:compile sass file and add style code into sass file and remove '@import compass/css3' because it give compile time error.