commenting out the 4 array CSR format codes so that i can get CI to work sooner for now, will revert later
in the sparse case, because an array could be empty, computing the min/max manifest address  can fail
cleanup naming in Numerical.Array.Mutable, switching from using least/greatest to min/max
still needed to deal with the maybeness of addresses for empty arrays
CSR api type checks! Still need to fixup walls and add testing though.
bump version of ghc 7.8 thats used for travis
placate -Wall wrt Numerica.Array.Layout.Sparse
added MVector instances for the Buffer types, still need to add the Vector instances too