Update package.js

Made github zipball URLs work properly.
Update package.js

Fixed missing ?
Find URL's filename and use that for the assetType
get assetType based on content disposition, not URL path.
Created test for assetType based on content-disposition.
Removed error throw per satazor
Updated package.js to emit warning rather than throw error on tar.gz
file. Updated tar.gz detection to use end of filename rather than match
any position in file. Updated test/package.js to check for warning on
tar.gz file.
Fixed code style based on jshint.
Update regexp and var definitions.
Merge remote-tracking branch 'upstream/master'
checkpoint commit