Pilosa: Add build step that generates static media assets for WebUI

[codysoyland]

This uses statik to generate Go files containing the static media assets needed to display the Pilosa WebUI. This allows the WebUI to be accessed by HTTP on port 10101 after invoking pilosa server.

This fixes FeatureBaseDB/general#27.

• Have you followed the guidelines for contributing?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing brew install <formula>)?

---

[codysoyland]

I would appreciate a review of this PR. We are close to cutting a new release soon and would love to have this merged prior to the release. Thanks!

[ilovezfs]

It would be far preferable to use a Go vendor directory for this.

glide, govendor, godep, and dep are some good choices for managing a vendor directory.

[codysoyland]

Pilosa already uses dep for library dependencies (recently switched from Glide). However, statik in this case is a binary dependency and is used as part of the build process (via go generate). As far as I'm aware, it is not possible to install a binary from a vendored dependency.

Here is a relevant ticket in the Glide issue tracker: Masterminds/glide#418

And here is an existing homebrew-core package that includes statik using the same method: https://github.com/Homebrew/homebrew-core/blob/master/Formula/aurora.rb

[codysoyland]

Would it be preferable to create a homebrew package for statik (similar to the glide one) and depend on it?

[codysoyland]

Closing this in favor of #16336, which combines this change with a version bump.