Draw lone electron pairs only for nitrogen containing species

@connie could you please merge 7401623c0d02ec748c4c36071931a8950f847bcc which draws lone electron pairs only for nitrogen containing species to the master and dev.rmg website. I think 7401623c0d02ec748c4c36071931a8950f847bcc is a better solution because the lone electron pairs only on nitrogen atoms alone are not helpful.