New theme: Slate

Switched to Slate theme from https://github.com/jasoncostello/slate
with a few modifications.

Signed-off-by: Esben Haabendal <esben@haabendal.dk>
Fixup blog post layout

Signed-off-by: Esben Haabendal <esben@haabendal.dk>
XD-tool 0.1.0 release

Signed-off-by: Esben Haabendal <esben@haabendal.dk>