TST: clean up spatial.distance tests.

Removed unnecessary test docstrings, cleanup up the ones with useful
info in them.  Also removed commented out code, unused imports, etc.
TST: clean up cluster tests for docstrings and pyflakes issues.

Also remove unused file vq_test.py.
TST: clean up tests for scipy.misc.  Also remove unused import.
TST: some minor cleanups in constants, odr and fftpack module.
Merge pull request #4296 from rgommers/test-cleanup

MAINT: some cleanups in tests of several modules