Move story styles into story.scss from common.scss

See crowdcover/crowdcover#295
Wrap what used to be `fieldset`s in `div.form-section`
Stylistic markup changes

Yeah. I'm changing whitespace here
Remove trailing whitespace and delete empty lines

Still adjusting whitespace. Sorry.
Section comments

That double as vim foldmarkers.
Moving rules around and putting them in sections
Trim down the styles for the map layer selection
Lighten up the styles of the report submit form
Decreasing the indent level of this hunk