fix lint errors
fix lint errors

bpietravalle/angularfire,FirebaseExtended/angularfire,denisKaranja/angularfire,yoda-yoda/angularfire,itxd/angularfire,bpietravalle/angularfire,itxd/angularfire,jamestalmage/angularfire,jamestalmage/angularfire,douglascorrea/angularfire,fbentz/angularfire,itxd/angularfire,nbr1ninrsan2/angularfire,denisKaranja/angularfire,FirebaseExtended/angularfire,cesarmarinhorj/angularfire,douglascorrea/angularfire,nbr1ninrsan2/angularfire,FirebaseExtended/angularfire,bpietravalle/angularfire,cesarmarinhorj/angularfire,fbentz/angularfire,douglascorrea/angularfire,fbentz/angularfire,yoda-yoda/angularfire,cesarmarinhorj/angularfire,jamestalmage/angularfire,nbr1ninrsan2/angularfire,denisKaranja/angularfire,yoda-yoda/angularfire