Add an online Editor for creating job submissions

[stestagg]

@salimfadhley / @lordmauve thoughts?

Change the main site layout to use flex-flow for putting the footer at the bottom of the page. This doesn't work in IE11, but just means that the footer floats up a bit on short pages (we don't have many) Also update map button styling, because google changed the look-and-feel of their buttons

the preview template is (largely) auto generated from the job.j2 jinja template by using nunjucks(https://mozilla.github.io/nunjucks/) with some minor tweaks. Editor code is pretty quick-and-dirty, but seems to work well in chrome. Also direct linking to pre-filled github PR, including filename generation (it's just a slug, so might collide with existing) Inline real-time checks of the meta (to complement, not replace the PR tests)

[lordmauve]

I like it a lot!

[stestagg]

cool :D, I'll merge it, and after the next build, can think about updating docs

[salimfadhley]

Amazing work!