Prioritize now_playing highlight group, but remove it from colorscheme

Reasoning for first: backwards compatibility. If user defined `now_playing`
highlight group it is what should be used.

Reasoning for second: it is useless there. If user has defined its own group its
effect will not be affected, if he has not then there is nothing to talk about.

powerline/config_files/colorschemes/default.json

@@ -28,7 +28,6 @@
 		"battery_gradient":          { "fg": "white_red", "bg": "gray0", "attr": [] },
 		"battery_full":              { "fg": "red", "bg": "gray0", "attr": [] },
 		"battery_empty":             { "fg": "white", "bg": "gray0", "attr": [] },
-		"now_playing":               "player",
 		"player":                    { "fg": "gray10", "bg": "black", "attr": [] },
 		"user":                      { "fg": "white", "bg": "darkblue", "attr": ["bold"] },
 		"superuser":                 { "fg": "white", "bg": "brightred", "attr": ["bold"] },

powerline/segments/common/players.py

@@ -50,7 +50,7 @@ class PlayerSegment(Segment):
 		stats['state_symbol'] = state_symbols.get(stats['state'])
 		return [{
 			'contents': format.format(**stats),
-			'highlight_group': ['player_' + (stats['state'] or 'fallback'), 'player', 'now_playing'],
+			'highlight_group': ['now_playing', 'player_' + (stats['state'] or 'fallback'), 'player'],
 		}]
 
 	def argspecobjs(self):