First draft of the introduction

Rewrote the introduction as a usecase.

Pulled the introduction into a separate file.

This is a first draft but thought I'd get out a general idea of the introduction I had out as soon as possible.
Maybe something like this: "Just like desktops and laptops, we use our mobile devices for both our social and entertainment needs. This includes taking pictures, and shooting videos." (here I try to keep the focus on the pictures and videos, since they are our target)