Add engines entry to package.json
Add engines entry to package.json

Fixes #1944

This adds an engines entry to package.json.
It's set to 4.1.1 which is the node version used in all electron
versions between 0.33.2 and 0.36.0 what covers the current (0.35.4).

Signed-off-by: Mathis Wiehl <1d6e1cf70ec6f9ab28d3ea4b27a49a77654d370e@mathiswiehl.de>

daaru00/kitematic,kitematic/kitematic,rlugojr/kitematic,kitematic/kitematic,daaru00/kitematic,rlugojr/kitematic,kitematic/kitematic,docker/kitematic,daaru00/kitematic,docker/kitematic,docker/kitematic,docker/kitematic,rlugojr/kitematic