Anet A8 x-belt tension block

For the new style Anet A8 x-carriage, the one with the nylon injected X axis parts. Also space for a teeth 16T bearing.

All the X axis tension blocks did not fit the new x-carriage snuggly because the dimensions changed. I redesigned the block for the new dimensions and so it uses two M5 bolts and nuts for more sturdiness.