Start 0.6.0-2 development.

d/changelog entries will be written on release
using the git commit messages.

Use 'gbp dch --since debian/0.6.0-1 --multimaint-merge'
to write d/changelog entries since that last release.

Gbp-Dch: ignore
Signed-off-by: Holger Levsen <holger@layer-acht.org>