Well,
Knowing basically nothing about modding Factorio I did try modifying version 0.18.7 and got it working (no extensive testing done though) :)
Versioning is wrong, but that should be possible to fix as well.
Basically i extracted the zip file, and modified the file info.json to the following content:
{
 "name": "WellPlanner",
 "version": "1.1.0",
 "title": "Well Planner",
 "author": "Gloin the Dark",
 "description": "Automatically layout pumpjack fields.",
 "factorio_version": "1.1",
 "dependencies": [
  "base >= 1.1.0"
 ]
}
Folder in the zipfile is still called WellPlanner_0.18.7
Zipfile itself is renamed to WellPlanner_1.1.0.zip
Using this new zip-file seems to be working so far....