Fixes for linux build

Jira issue: wp-882
Changed to use node-open module

Applauncher now uses the node-open module for better cross-platform support.

Also added applauncher test widget

Jira-issue: wp-882
Added open module to package.json

Used to launch applications in a cross-platform manner.

Jira-issue: wp-882
Merge pull request #540 from TobyEalden/wp-881-pr

Fixes to applauncher API for Linux