fdsn/get_stations_bulk cross-implemented with fdsn/get_waveforms_bulk

Removing make_pep8.py

(also updated docker hub base image, the base image was xenial due to
some mistake when setting up the base image..)

Conflicts:
	obspy/clients/fdsn/mass_downloader/download_helpers.py
	obspy/io/stationtxt/core.py

remove all usages of future.standard_library

* adjust tolerance for farfield test case

see #1642

see http://tests.obspy.org/70729/#1

* again try to fix farfield test case, see provious commit

* farfield test minor tolerance adjustments again

Conflicts:
	obspy/CONTRIBUTORS.txt

earthworm client: Inline tracebuf extraction to minimize copying data.