Added 20 sets to [DGC] Collection

Previews & DDL:

	[DGC] 2011.02 No.921 Nao Yuuki 優木菜緒
	[DGC] 2011.02 No.922 Yuri Nagata 永田ゆうり
	[DGC] 2011.02 No.923 Ayana Maeda 前田彩七
	[DGC] 2011.03 No.924 Yuuri Morishita 森下悠里
	[DGC] 2011.03 No.925 Ayumi Takahashi 高橋亜由美
	[DGC] 2011.03 No.926 Mui Kuriyama 栗山夢衣
	[DGC] 2011.03 No.927 Rina Kato 加藤リナ
	[DGC] 2011.03 No.928 Nana Ogura 小倉奈々
	[DGC] 2011.03 No.929 nao
	[DGC] 2011.03 No.930 Chiri Arikawa 有川知里
	[DGC] 2011.03 No.931 Nanako Tachibana 橘奈々子
	[DGC] 2011.03 No.932 Kana Houjyou 北条佳奈
	[DGC] 2011.04 No.933 Risa Yoshiki 吉木りさ
	[DGC] 2011.04 No.934 Misaki Nito 仁藤みさき
	[DGC] 2011.04 No.935 Arisa Kuroda 黒田有彩
	[DGC] 2011.04 No.936 Gujikita Ayaka 藤北彩香
	[DGC] 2011.04 No.937 Naruse Kokomi 成瀬心美
	[DGC] 2011.04 No.938 Otone Nana 乙音奈々
	[DGC] 2011.04 No.939 Haraka Andou 安藤遥
	[DGC] 2011.04 No.940 Marina Yamasa 山咲まりな