Add how_we_found_these_blog_posts msg.

Pretty much same as twitter one for now.
comment out upload_wordpress_key var in categoryHeading ctrl

We're not ready to show this yet.
commit with compiled impactstory.js

i think it didn't have enough time to complile before my last commit. arg.
catch errors caused by no tips string in db.
clearer styling for 'import' link in category-heading tips.