debian/control: add missing dependency on ruby-spring
debian/control: add missing dependency on ruby-spring

It is already recommended by rails, but it will not be installed on some
scenarios. Since it is mentioned in the Gemfile, let's depend on it
directly.

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