Update draganddrop.js

Add channel information to the dataTransfer and expose it on drop.
Merge pull request #1 from Marc-Andre-Rivet/mrivet-on_drop_channel_info

Update draganddrop.js
Update draganddrop.js

Did not work in IE11, need to put everything in "Text"
Update index.html

Documentation update for $channel
Update draganddrop.js
Update draganddrop.js
Merge pull request #44 from Marc-Andre-Rivet/master

Adding $channel information on drop