Added node.js v4.0 and v4.1 to travis tests
Added node.js v4.0 and v4.1 to travis tests

josdejong/mathjs,FSMaxB/mathjs,FSMaxB/mathjs,FSMaxB/mathjs,josdejong/mathjs,FSMaxB/mathjs,josdejong/mathjs,josdejong/mathjs,devanp92/mathjs,FSMaxB/mathjs,mcanthony/mathjs,josdejong/mathjs,luke-gumbley/mathjs,mcanthony/mathjs,luke-gumbley/mathjs,devanp92/mathjs