package.json: rename theme name from Casper to Coldnew
package.json: rename theme name from Casper to Coldnew

This is my own theme, which will contains my own config.

Signed-off-by: Yen-Chin Lee <082d453d72dce940e12089a4ad48b97cfe1f3ec4@gmail.com>

coldnew/ghost-blogit-theme