obspy Stream plot wiggle ready

Simple wiggle plot based on Caparica's code.
Fixed travis and PEP8 code style.

Insert correct expections, removed spaces. Added obspy to travis.
Merge branch 'leouieda/master' into vis.mpl.wiggle

Conflicts:
	.travis.yml copied from 'leouieda/master' added obspy
Merge branch 'vis.mpl.wiggle' into utils_obspy

Since booth cover small obspy features I am merging them.