Fix for getAlbums: HTTP error 401

[bbrewington]

I'm getting "Error in open.connection(con, "rb") : HTTP error 401." when I run the following:

getAlbums("3z6Gk257P9jNcZbBXJNX5i", type = "album", market = "US")
# this is using the Regina Spektor artist id provided in the readme

Solves a couple issues I found in the getAlbums function:

1. 401 unauthorized error because no token involved
2. The string "/albums??&album_type=album" seems to be an invalid URL format
3. I converted the jsonlite::fromJSON calls to httr::GET to allow for the httr::config(token = token) argument

getAlbums <- function(id, type = "album", market = "US", token)
{
  require(dplyr)
  total <- httr::content(httr::GET(paste0("https://api.spotify.com/v1/artists/", 
                                     id, "/albums?album_type=album"),
                     httr::config(token = token)))$total
  req <- httr::GET(paste0("https://api.spotify.com/v1/artists/", 
                                   id, "/albums?offset=0&limit=", total, "&album_type=", 
                                   type, "&market=", market),
                   httr::config(token = token))
  return(lapply(httr::content(req)$items, 
                function(x) data.frame(
                  id = x$id, 
                  name = x$name, 
                  album_type = x$album_type, 
                  available_markets = paste(x$available_markets, collapse = ", "),
                  stringsAsFactors = F)) %>% 
           bind_rows())
}