This reverts commit 7e3bc5ee.

Theia does not seem to be ready for this version, several things are not
working:
 - selecting another python interpreter
 - linting in the editor
 - at startup there's always a "Python is not installed.Please download
and install Python before using the extension." warning . I think this
happened sometimes with the previous version too.

jedi was working fine, but too maybe critical features are broken.