Remove git submodules, so that git clone of Wekan repo works now on Windows. Closes #977

CHANGELOG.md

@@ -5,7 +5,8 @@ This release fixes the following bugs:
 * [Fix importing Trello board: Attribute correct members to their
    comments](https://github.com/wekan/wekan/pull/1080);
 * [Fix Case-sensitive email handling](https://github.com/wekan/wekan/issues/675);
-* [Use fibers 1.0.15 because 2.0.0 is broken](https://github.com/wekan/wekan/commit/86e2744c24149c0eacf725b68a186d0bcfae5100).
+* [Use fibers 1.0.15 because 2.0.0 is broken](https://github.com/wekan/wekan/commit/86e2744c24149c0eacf725b68a186d0bcfae5100);
+* [Remove git submodules, so that git clone of Wekan repo works now on Windows](https://github.com/wekan/wekan/issues/977).
 
 Thanks to GitHub users GhassenRjab, nztqa and xet7 for their contributions.