Okay, I've manually fixed it by finding those JAR files that fail to download in log (see previous post where I found them)... I then put those files into the folder the installer extracts them to.
C:\Users\<YOUR USER>\AppData\Roaming\.minecraft\libraries\net\minecraftforge
\accesstransformers\2.1.3-shadowed\accesstransformers-2.1.3-shadowed.jar
\eventbus\2.2.1-service\eventbus-2.2.1-service.jar
Done... fixed...