Bump version to 2.1.11

Fallback to RADICALE_CONFIG from OS environ

Specify encoding for test files

"utf-8" is not the default encoding on Windows, causing tests to fail

Bump version to 2.1.8

Bump version to 2.1.7

Skip test creating principal with whitespaces on Windows

It's not allowed by the file system.

Bump version to 2.1.5

Bump version to 2.1.4

Improve Dockerfile (Kozea#676)

* fixing DockerFile

* applying corrections

* fixating the dest file

Bump version to 2.1.2