Initial support for the related_posts plugin.
Initial support for the related_posts plugin.

(cherry picked from commit 0e629861c43cf0a80acced231e854b46e88a2d95)
Signed-off-by: Sascha Wagner <5b08bdb72bb1c2810fe64e2d5f186da64da75f68@gmail.com>

sashw/Flexmod,sashw/Flexmod,sashw/Flexmod