Fix archive links

So that they match the anchors generated on the archive pages
Atom feed should use absolute URLs

For both the full content and the excerpt.
Use Post.ContentExcept for the summary
Teach FolderCopy to understand the "." destination

Additionally, we should overall any files when we are performing a copy.
Work nicely with urlFormats that include '.html'
Generate drafts correctly as named html files
Merge pull request #101 from DanRigby/FixArchiveLinks

Fix archive links
Merge pull request #102 from DanRigby/UseAbsoluteUrlsInAtomFeed

Atom feed should use absolute URLs
Merge pull request #103 from DanRigby/HandlePeriodInDirectoryCopy

Teach FolderCopy to understand the "." destination
Merge pull request #105 from GeorgeHahn/fileslugs

Work nicely with urlFormats that end in '.html'