Added extra hv.util.output unit test and four tests for hv.util.opts
Added extra hv.util.output unit test and four tests for hv.util.opts

basnijholt/holoviews,ioam/holoviews,ioam/holoviews,basnijholt/holoviews,basnijholt/holoviews,ioam/holoviews