Add jsconfig.json
Add jsconfig.json

This file enables type checks for JavaScript in Visual Studio Code. It
currently causes some error markers in the editor, but these do not pose
a problem in the grunt build. The markers can be eliminated gradually by
adding more jsdoc comments or d.ts files.

Change-Id: Ic4907129bca850d805762fcbdcf4c391d6c4f08f

eclipsesource/tabris-js,eclipsesource/tabris-js,eclipsesource/tabris-js