update old ObsPy version number use in two places
Changelog for 0.8.4
deb: manually remove one .gitignore during packaging

no idea why it gets included in the package building process in the
first place. several other .gitignore files get excluded automatically.
Throw verbose exception if no data has been added before plotting
Merge pull request #591 from bmorg/ppsd_plot_exception

Throw verbose exception if no data has been added before plotting
quakeml: reset patched RelaxNG schema

 - official version again (which has been fixed)
 - basically QuakeML-RT tags are now allowed as valid foreign tags
   (as is tolerated by QuakeML developers)
deb packaging: avoid problems/workaround with https and SSL
obspy-plot: option "-o" for direct output to file (via
Stream.plot(outfile))
trivial helpstring change