Best Answer - Chosen by the Asker
Ryoko and Hello CTHULHU san are correct.
I've just found that meaning here.
http://dictionary.goo.ne.jp/leaf/jn2/78449/m0u/%E3%81%94%E3%81%96%E3%82%8B/
６ （補助動詞）補助動詞「ある」「いる」の意の丁寧語。…でございます。…ております。
「おざれ事で―・らう」〈虎清狂・鈍根草〉
[補説]室町時代から江戸時代までは広く用いられたが、否定形には室町時代には「ござない」が、江戸時代では「ござらぬ」が使われた。また、江戸時代に入ると「まする」「ます」を伴う形がしだいに一般化し、現代では特殊な場合を除いて「ございます」の形が普通になった。
I will explain it briefly. ''Gozaru" means the polite words of "aru" and "iru"
This word was used in Muromachi era to Edo era. Negative form ''Gozanai" was used in Muromachi era but it was changed into "Gozaranu" in Edo era.
In Edo era, "Gozaru" was changed into "Masuru" and "Masu" as a generalization. Now, except special occasions, ''Gozaimasu" becomes usual.
Thank you for your question, I got a real answer about "Gozaru".
I think most Japanese do not know about this.
Actually, modern Japanese recognize "Gozaru" as "Masu".
