Integrate all node.js module 'opn' features

Set original feature as the default behaviour.
NEW FEATURE: Setting per language for which app to use
NEW FEATURE: Setting per language to pass argument(s) to app
NEW FEATURE: Setting per language to open file URL in local web server
NEW FEATURE: Setting per language to use file system path, instead of URI
NEW FEATURE: Setting per language to wait for the opened app to exit before calling the callback

Tested with VS Code v0.10.8 in MS Windows 10 Pro environment.

Initial version published to MS VS Code Extension Gallery

Tested with VS Code v0.10.8 in MS Windows 10 Pro environment.

Initial release

Tested with VS Code v0.10.8 in MS Windows 10 Pro environment.