Added sp_bin option to spotify-widget

Allows specifying a custom location for the sp binary via widget config.
This is intended for users who don't want to add the sp binary to their
system PATH.

spotify-widget/spotify.lua

@@ -12,9 +12,6 @@ local awful = require("awful")
 local wibox = require("wibox")
 local watch = require("awful.widget.watch")
 
-local GET_SPOTIFY_STATUS_CMD = 'sp status'
-local GET_CURRENT_SONG_CMD = 'sp current'
-
 local function ellipsize(text, length)
     -- utf8 only available in Lua 5.3+
     if utf8 == nil then
@@ -39,6 +36,10 @@ local function worker(user_args)
     local max_length = args.max_length or 15
     local show_tooltip = args.show_tooltip == nil and true or args.show_tooltip
     local timeout = args.timeout or 1
+    local sp_bin = args.sp_bin or 'sp'
+
+    local GET_SPOTIFY_STATUS_CMD = sp_bin .. ' status'
+    local GET_CURRENT_SONG_CMD = sp_bin .. ' current'
 
     local cur_artist = ''
     local cur_title = ''