Exclude images from being bundled with gem

[m-r-mccormick]

PR #1124 was split into two PRs, this being one of them. This excludes images from being included in the gem file which propagates to downstream sites. search.svg is the only image file remaining which is used in downstream sites, although I couldn't find it referenced anywhere in the project, and excluding it doesn't appear to negatively impact downstream sites. In addition, search.svg doesn't appear to be the same search icon used in the search input of downstream sites: They are different orientations and shapes/sizes.

This excludes from downstream sites:

assets/images/large-image.jpg
assets/images/small-image.jpg
favicon.ico

[mattxwang]

Is there a reason that we're ignoring the favicon? My understanding is that we intentionally package it by default (since it beats not having a favicon) - see it being included in the .match statement.

[m-r-mccormick]

I don't have a solid reason, and I think you are right that having it as a default is better than not having one. Just pushed an update.

[mattxwang]

Thanks for the quick turnaround. Testing locally, the new git ls-files command works as intended.

We'll only really get this tested when I actually push out the next release, but I think I'm happy to merge this in as-is. Thanks for your contribution!