Fixed incorrect install instructions in README
Fixed incorrect install instructions in README

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