Extract generic code into github.com/weaveworks/gitops-toolkit

[luxas]

• Refactor the internal code to be generic and not have import loops Split packages so we can extract gitops-toolkit #347
• Publish staging repository to use: https://github.com/luxas/gitops-toolkit
• Move ignite over to use the gitops toolkit from the staging repo Switch imports to gitops-toolkit #354
• Move to weaveworks/gitops-toolkit
• Update references in ignite to weaveworks/gitops-toolkit Switch to using weaveworks/gitops-toolkit #359
• Improve the gitops toolkit and tag an initial "release"

[luxas]

cc @stealthybox

[luxas]

Fixed with #372