see #548, different way to handle multiple sampint

this should just show an alternative possibility to handle multiple
sampling rates for obspy-scan.
adding test for obspy-scan

* adding test for obspy-scan by comparing png output
* making obspy-scan more robust against sampling_rate=0 and funky station
  names
fdsn: tests for client with authentication
fdsn: add authentication
fdsn: fix/adjust (doc)tests

@krischer: py.test is not checking doctests by default
fdsn: fix Client.help()
Merge pull request #649 from obspy/fdsn_auth

fdsn client with authentication
fdsn: some minor changes and refactoring

 - new method to fetch the actual, full version numbers of webservices
 - insert method numbers into help() message and Client.__str__()
 - refactoring
 - adapt tests for version number in strings
fix tests
updating python coverage link to coverall

closes #648
correct syntax, see #642

to my knowledge no "normal arguments" are allowed in python after a keyword
argument was already specified.
Adding warning for problematic ids
travis ping
Merge pull request #647 from mbyt/obspy-scan-tests

Obspy scan tests
print environment variables in travis

currently strange test problems in travis, this might help in the future
to check on changes/problems with environment variables.
fdsn: add tests for bulk waveform download
fdsn: work on bulk waveform requests
fix test with StringIO and check for "read" attribute even if input has
"__iter__" because of StringIO
fdsn: implement bulk requests using list of net/sta/loc/cha/t1/t2 lists
as input
docstring