Add plugin support

[DinisCruz-Dev]

The idea is to keep the nwr package/app focused on the core environment and move the more advanced features (and extra stuff) into separate plugins (which can then be loaded dynamically and installed from the app).

• good examples of plugins to add:
  • WebDriver/Selenium support (which at the moment is part of the the NWR code base)
  • Other language support (like Javacript Re-add javascript support (as a optional execution language) #13, ClosureScript add clojurescript support to REPL #7, C# (via https://github.com/tjanczuk/edge), etc...)
  • weinre try weinre for same screen coding and debugging #23
  • golden-layout Create PoC of using Golden-Layout for creating multi tab support #28
  • TiddlyWiki: https://github.com/Jermolene/TiddlyWiki5