ENYO-2950: allow to have  a file name with capital file extension into package.js

Enyo-DCO-1.1-Signed-off-by: Junil Kim <logyourself@gmail.com>
Merge pull request #510 from enyojs/ENYO-2950

ENYO-2950: allow to have  a file name with capital file extension into package.js

Reviewed-By: Ben Combee (ben.combee@lge.com)