Create viz.yaml storm outline

[aappling-usgs]

Populate the viz.yaml from #1 with core components expected for every storm. Use this opportunity to revise and clarify the viz.yaml organization.

• Every item name should be extremely clear and intuitive to newcomers.
• There should be no vestigial viz.yaml comments, and there should be new comments where these would aid in use of the template. Maybe there's even a 1-sentence comment describing each viz item, to ease adoption of the template by new teammates.
• Organize the viz items in a very sensible/chronological order.
• Use our new vizlab style guide in naming elements, functions, and scripts.

Components (check and revise this list; look to recent vizzies to establish expected inputs and outputs of each viz item):

• parameters: date range, etc.
• base map
• gage locations
• flood stage info for each site
• timesteps
• storm track
• precip
• stage timeseries data
• legend
• sparklines
• caption
• social media
• header and footer
• thumbnails
• GIF
• js resources (animate, lightbox)
• css files
• play and loading icons

Distinguish mobile from desktop, as we have in recent vizzies. Mobile first!

Placeholders:

• leave empty, or with TODO, items that will be new for each vizzie. e.g. overall viz id, name, date, publish-date, path, analytics-id, description, some keywords. it should be really hard to accidentally forget to update any of these when forking and using this template.