It seems like some of the files listed on the most recent build dont actually exist at the locations specified. I've tried downloading them manually and no luck with
http://files.minecraftforge.net/fmllibs/bcprov-jdk15on-148.jar
http://files.minecraftforge.net/fmllibs/scala-library.jar
I was able to steal those files from another version of tekkit server I had around and put them into my lib folder. It seems to have done the trick.