[NOT READY] Copy

plug into tilelive.copy function

cc @rclark 
I would rather `mapbox-tile-copy src dst --withoutprogress` than `mapbox-tile-copy src dst --withoutprogress=true`. The double-negative default is confusing me @_@.

Also, if we are reporting progress, where will we write/apply the reporting function? It would be nice to keep all the `console.log`ing in this script if possible.