Another attempt at making d-yaml work with dub.

Creating a symlink in source to the dyaml directory does not actually
result in a symlink when another package grabs d-yaml as a dependency
via dub, and even if it did, it wouldn't work on Windows. So, this moves
the source into source so that it'll actually work, and cdc.d has been
adjusted accordingly so that building with it should still work.
Merge pull request #7 from jmdavis/dub

Another attempt at making d-yaml work with dub.