Reduce some image sizes

[nwinter]

Auto-compressed many marketing pages images with ImageOptim; resized some large headshots and one jumbotron.

I noticed while evaluating China bandwidth needs that some of these images are much bigger than they need to be, with some images clocking in at 4.5MB or 9.5MB. When Dexecure is enabled, it mostly takes care of auto-resizing and auto-compressing these, but it doesn't always get everything, some race condition for the first images to be requested on home page perhaps. When we are in China mode, we have not yet enabled Dexecure, so our users bear the brunt of large image downloads.

ImageOptim is an automatic image filesize compressor program that makes images as small as it can without changing quality, dimensions, or file format. I dropped several marketing page folders' worth of images in there after a quick look on where some big ones are.

I also resized some avatars on /about from full resolution to the 100px squares that the other ones on that page are at. And I resized the max width of /parents page jumbotron from almost 5000 pixels to 2560px like our home page jumbotron.

Overall, this should save user some bandwidth, especially when Dexecure isn't around, with no compatibility issues.

[AndrewJakubowicz]

I tested this locally. Looks good. From eyeballing local and production is doesn't look like it has decreased any image quality that would be of concern.

[AndrewJakubowicz]

We needed certain home page icons to be much higher quality. I think we may want to either re run the optimizer on the conflicted files ensuring high resolution. Or exclude them from this PR.
Thanks