Slim down the about page
Fix typo
Fix up h1 alignment
Paragraphs are paragraphs.
Make images in grid columns not overflow
Fill in existing screenshots and copy to TS and RP pages
Rename these pages to more generic urls

Since we'll eventually migrate to THE ONE TRUE WHISPER APP, let's
get away from embedding RedPhone and TextSecure in the url structure.
Remove /security, add developers/labs