Add homepage logos for any upcoming events (for devopsdays-theme release)

[mattstratton]

See devopsdays/devopsdays-theme#49 for details

[mattstratton]

Actually, see devopsdays/devopsdays-theme#81 for details.

[mattstratton]

Long story short - if they have a logo, crop it to 500px square and dump it into static/events/YYYY-CITY/logo-square.png

If they don't, grab it from twitter.

[bridgetkromhout]

• I've got reasonable-ish logos for almost all of them (Los Angeles doesn't have a twitter account or a logo).
• I didn't try to make them all exactly 500px - does that matter?
• I did change all of them to jpgs as discussed in Change from png to jpg for images as much as possible devopsdays-theme#150.
• Are we actually going to need to name the file in every event's yaml? Wouldn't a default with an override-if-desired make sense?

[bridgetkromhout]

@mattstratton Thanks for approving the merge - I forgot to name you in the questions above.

[mattstratton]

The file check is actually pretty annoying, code-wise, and I like people having the flexibility to name it whatever they want. I think if it's the default option in the generator, it's not that big of a deal.

[mattstratton]

I might start resizing smaller than 500 px square because that might be a little too big. But it should probably be fine.

[bridgetkromhout]

The file check is actually pretty annoying, code-wise, and I like people having the flexibility to name it whatever they want. I think if it's the default option in the generator, it's not that big of a deal.

Okay. Then I think a to-do before this is is for me to add the relevant line to every 2017 event's yaml.