this changes the Dockerfile a bit to work with the current version
0.10.0 of writefreely, and removes the docker-setup script for now.
Kind of a work in progress but wanted to share with those interested.
This upgrades the library to v2, which lets you specify that GOMAXPROCs
should always be the max number of CPUs -- and then sets it to that.
One side effect of this is that images are no longer listed in sitemaps.
I'm somehow at a loss on how to build and append the images array we
need, with the library's latest changes.
Fixes#86
