Zerobot compact shell

I removed the wheel humps because I wanted to be able to print it on upside down to save support material and to be able to use different sized wheels. I am still printing it right now so I don't know how it will turn out. I used the files from the Reinforced Top by ManAtArmsProps and the zerobot bottom shell by Maverick_Makes because they were easier to print than the original files. I might make it even slimmer in the future to save space.