First draft of the introduction

Rewrote the introduction as a usecase.

Pulled the introduction into a separate file.
Incorporate most review comments.

Nearly all review comments are done. Except for the first line of the
introduction.
Merge remote-tracking branch 'origin/master' into 244-use-case-introduction

Conflicts:
	report/droidstealth.tex
Added paper structure

Added a paper structure to the end of the introduction.

Updated the introduction sentence to incorporate review comments.
Include anecdote about need for hiding data.

Paragraph about the arab spring and crackdowns on phone journalism has
been added.
Change paper topic sentence in intro.

Based on review comments.
Incorporate review comments
Merge pull request #245 from droidstealth/244-use-case-introduction

First draft of the introduction