client -> courier, server -> courierd

--HG--
rename : client/client.go => courier/client.go
rename : client/config.go => courier/config.go
rename : client/download.go => courier/download.go
rename : client/register.go => courier/register.go
rename : client/upload.go => courier/upload.go
rename : server/authenticated.go => courierd/authenticated.go
rename : server/config.go => courierd/config.go
rename : server/server.go => courierd/server.go
rename : server/shortcode.go => courierd/shortcode.go
rename : server/unauthenticated.go => courierd/unauthenticated.go