Fixed using too much memory

Hi.

Thanks for the gem.

I found the problem. It is using too much memory, when post the type of text with the tumbr-rb gem, the gist of the following link.

https://gist.github.com/4362220/1ab009452fd525cd9da36258fe23b1552afadc11

I made ​​a patch.

Please check this problem & my patch!