Reverted travis to numpy 1.9.1
Reverted travis to numpy 1.9.1

Conda numpy and matplotlib versions don't play nicely together
causing an import failure of the multiarray module

vascotenner/holoviews,ioam/holoviews,ioam/holoviews,vascotenner/holoviews,mjabri/holoviews,mjabri/holoviews,ioam/holoviews,vascotenner/holoviews,basnijholt/holoviews,basnijholt/holoviews,basnijholt/holoviews,mjabri/holoviews