Allow for editing of market fields

[davidhperry]

Sometimes the fields for WSX markets will have to be edited, to account for typos and other situations. For example, when a market is a long time off, the title and/or description will read 'Democrat Wins Elected President in 2024.' Once the individual is known, we will update the market to reflect that info, 'Judy Smith (D) Elected President in 2024.'

I'm not a stickler for how we do this, at least initially. Ideally, one could navigate the site with administrative permissions and make in-line edits on the page, but I'm open to other approaches.