fix(dnd.js): not all files in dropped folder are read

`readEntries` was only being called once.  Now, it is called
until failure or until the success callback yields an empty
array of entries.

fixes #1217

[skip ci]
chore(uploader-demo-jquery.js): remove redundant option
chore($build): inc build num

This marks the new release candidate for 5.0.
#1217