prune README
prune README

Remove all "redundent" information from the README and place all the
badges at the top.

I guess, the depth of the README is a matter of choice? But perhaps
avoiding duplication is a goal worth pursuing?

numba/numba,cpcloud/numba,IntelLabs/numba,IntelLabs/numba,cpcloud/numba,cpcloud/numba,IntelLabs/numba,numba/numba,numba/numba,IntelLabs/numba,cpcloud/numba,numba/numba,cpcloud/numba,IntelLabs/numba,numba/numba