rails4: fix size to nil instead empty string (do not use to_s)
rails4: fix size to nil instead empty string (do not use to_s)

EcoAlternative/noosfero-ecosol,marcosronaldo/noosfero,macartur/noosfero,blogoosfero/noosfero,vfcosta/noosfero,vfcosta/noosfero,CIRANDAS/noosfero-ecosol,evandrojr/noosfero,CIRANDAS/noosfero-ecosol,macartur/noosfero,AlessandroCaetano/noosfero,AlessandroCaetano/noosfero,AlessandroCaetano/noosfero,marcosronaldo/noosfero,LuisBelo/tccnoosfero,arthurmde/noosfero,coletivoEITA/noosfero-ecosol,arthurmde/noosfero,tallysmartins/noosfero,LuisBelo/tccnoosfero,EcoAlternative/noosfero-ecosol,samasti/noosfero,alexandreab/noosfero,EcoAlternative/noosfero-ecosol,AlessandroCaetano/noosfero,coletivoEITA/noosfero-ecosol,CIRANDAS/noosfero-ecosol,alexandreab/noosfero,coletivoEITA/noosfero-ecosol,larissa/noosfero,larissa/noosfero,tallysmartins/noosfero,larissa/noosfero,AlessandroCaetano/noosfero,LuisBelo/tccnoosfero,larissa/noosfero,tallysmartins/noosfero,EcoAlternative/noosfero-ecosol,EcoAlternative/noosfero-ecosol,evandrojr/noosfero,alexandreab/noosfero,blogoosfero/noosfero,larissa/noosfero,blogoosfero/noosfero,coletivoEITA/noosfero-ecosol,arthurmde/noosfero,samasti/noosfero,blogoosfero/noosfero,macartur/noosfero,tallysmartins/noosfero,tallysmartins/noosfero,vfcosta/noosfero,samasti/noosfero,EcoAlternative/noosfero-ecosol,vfcosta/noosfero,CIRANDAS/noosfero-ecosol,evandrojr/noosfero,evandrojr/noosfero,alexandreab/noosfero,arthurmde/noosfero,evandrojr/noosfero,arthurmde/noosfero,marcosronaldo/noosfero,marcosronaldo/noosfero,larissa/noosfero,blogoosfero/noosfero,arthurmde/noosfero,alexandreab/noosfero,AlessandroCaetano/noosfero,LuisBelo/tccnoosfero,blogoosfero/noosfero,larissa/noosfero,evandrojr/noosfero,tallysmartins/noosfero,macartur/noosfero,blogoosfero/noosfero,macartur/noosfero,coletivoEITA/noosfero-ecosol,macartur/noosfero,coletivoEITA/noosfero-ecosol,macartur/noosfero,arthurmde/noosfero,LuisBelo/tccnoosfero,marcosronaldo/noosfero,AlessandroCaetano/noosfero,samasti/noosfero,EcoAlternative/noosfero-ecosol,alexandreab/noosfero,LuisBelo/tccnoosfero,vfcosta/noosfero,tallysmartins/noosfero,marcosronaldo/noosfero,samasti/noosfero,evandrojr/noosfero,samasti/noosfero,CIRANDAS/noosfero-ecosol,vfcosta/noosfero,alexandreab/noosfero,marcosronaldo/noosfero