Make SciPy version dependency explicit.
doc: Load clustering example data via NumPy.

It's more secure than pickling, and smaller, too.
doc: Replace hcluster with SciPy functions in example.
Update FDSN doctest.
Merge pull request #920 from QuLogic/scipy-cluster

Updated clustering example
FDSN now does the same when debug is on...
Fixing FDSN doctests
Adapting FDSN tests to latest IRIS changes
doc: Fix clustering example when using URL.
doc: Update documentation copy of clustering example.

Refs #920.