Refactor: extract functional parts of `weave export` so they can be called from elsewhere
Refactor: extract functional parts of `weave export` so they can be called from elsewhere

weaveworks/weave,n054/weave,paulbellamy/weave,n054/weave,weaveworks/weave,n054/weave,weaveworks/weave,n054/weave,weaveworks/weave,paulbellamy/weave,paulbellamy/weave,paulbellamy/weave,n054/weave