Ngx-bootstrap: feat(plunker): create plunker for each demo

[markpritchett]

I think it would be useful to the community if each demo had a plunker. This would bring consistency with how demos are done on angular.io.

[valorkin]

I want it soo much! And we are working on bringing new docs, so I hope it will happen soon

[valorkin]

couple of steps in this direction is made:

• converted bundles from system.js to UMD
• created base plunker for issues http://bit.ly/ng2-bootstrap-plnkr