Improve landing page

I have improved the landing page by changing the styling, but also
adding content. It is still pretty simple, but at least there is now
enough content. I will still have to add some bits in the future.

I have removed the carousel captions and moved the carousel bullets
below the images. Also the images themselves are now much larger. For
the content I use two sections. One describing the features and another
one explaining how the whole process works.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>