center content of index page

The content of the index page is centered.
`col-md-7` is a bootstrap class and it's not a good idea to add style to the classes of other frameworks. With the following setup every other `col-md-7` blocks in the project will have centered text, even where we don't want them. 

The best way is to apply a new class to the block that you want to center and then in the media query apply to it `text-align: center`.