Move require() for node-get so it's not a hard depend.
Move require() for node-get so it's not a hard depend.

topwood/tilelive,mapbox/tilelive.js,kyroskoh/tilelive,tomhughes/tilelive.js,gravitystorm/tilelive.js,paulovieira/tilelive,mapbox/tilelive,nyurik/tilelive.js,Norkart/tilelive.js