Add sitemap files to generate, Add fix for localhost references in static files.

[joshgerdes]

Add Ghost sitemap files, whether linked or not, to generate function of buster.

[joshgerdes]

There are actually 2 separate changes but for some reason I could not adjust this pull request to point to a specific commit.

The second addition adds a section to fix localhost references in static files. It introduces a new argument (--new-domain) to be used to replace the localhost URLs.

This addition is useful with paired with the sitemap addition because the sitemap files are generated with localhost URLs.

[joshgerdes]

FYI, looks like this would fix issue #26.

[shavo007]

will this be merged soon!?

[m1guelpf]

ping @axitkhurana