Add vim modeline

vim modeline for all the Python files so that it's easier to
follow the coding style guideline.
autobuild: Remove

We only build on demand.
repoweb: Remove

We don't show build results, at least not yet. If we'll ever need this
again it must be implemented from a Web application.
Rewrite Snapshot to be a class

This is simpler, cleaner, and most importantly - faster, since we
avoid creating the component dictionary repeatedly.