API: use json objects instead of keys for listing (tags)

[radhta]

Current:

			"tags": {
				"111": "electro",
				"23": "electronic",
				"243": "soundtrack",
				"307": "synthwave",
				"1558": "video.game",
				"8": "trance"
			},

Desired:

"tags": [
    {
        "genreid": 111,
        "genrename": "electro"
    },
    {
        "genreid": 23,
        "genrename": "electronic"
    },
    {
        "genreid": 243,
        "genrename": "soundtrack"
    },
    {
        "genreid": 307,
        "genrename": "synthwave"
    },
    {
        "genreid": 1558,
        "genrename": "video.game"
    },
    {
        "genreid": 8,
        "genrename": "trance"
    }
],