Update README with npm install instructions.
Update README with npm install instructions.

zhm/tilestream,simonpoole/tilestream,makinacorpus/tilestream,mapbox/tilestream,makinacorpus/tilestream,mapbox/tilestream,NolaMark/tilestream,staltz/tilestream,markng/tilestream,staltz/tilestream,zhm/tilestream,simonpoole/tilestream,markng/tilestream,HydroLogic/tilestream,frankrowe/tilestream,NolaMark/tilestream,HydroLogic/tilestream,frankrowe/tilestream