register("path/to/asset")

Register an asset. Returns a unique key which is

the unique URL where the asset can be accessed. For example:

julia> key = AssetRegistry.register("/Users/ranjan/.julia/v0.6/Tachyons/assets/tachyons.min.css")
"/assetserver/97a47bdda5bd9274ad1a9cd10a0337f3b033a790-tachyons.min.css"