Update .travis.yml for LTS 4/GHC 7.10.3
Update .travis.yml for LTS 4/GHC 7.10.3

anton-dessiatov/stack,AndreasPK/stack,phadej/stack,mrkkrp/stack,Blaisorblade/stack,deech/stack,narrative/stack,AndrewRademacher/stack,MichielDerhaeg/stack,AndrewRademacher/stack,narrative/stack,Fuuzetsu/stack,deech/stack,Fuuzetsu/stack,harendra-kumar/stack,MichielDerhaeg/stack,martin-kolinek/stack,mrkkrp/stack,Heather/stack,Blaisorblade/stack,anton-dessiatov/stack,luigy/stack,harendra-kumar/stack,phadej/stack,martin-kolinek/stack,achernyak/stack,sjakobi/stack,Heather/stack,juhp/stack,sjakobi/stack,achernyak/stack,juhp/stack,AndreasPK/stack,luigy/stack