Bug in processing traces with sampling_rate 0 (e.g. log files)

[megies]

I think this is a bug:

jane/src/jane/waveforms/process_waveforms.py

Lines 101 to 105 in 525c172

	if any(tr.stats.sampling_rate == 0 for tr in stream):
	starttime = min(tr.stats.starttime for tr in stream)
	endtime = max(tr.stats.endtime for tr in stream)
	if starttime == endtime:
	starttime += 0.001

I guess what was intended was to increment endtime instead. Currently, such files can not be indexed showing the following error (even though the value of indexing such files is extremely doubtful, see #89):

[2018-07-23 11:48:01,313] DEBUG: Error indexing '/local_home/jane/archive/2018/BW/MSBB/LOG.L/BW.MSBB..LOG.L.2018.101': '<class 'django.db.utils.DataError'>' - range lower bound must be less than or equal to range upper bound