DOC more complete coverage of API linking in examples

Previously ignored non-plot files.

Avoids some link over/undergeneration
TST add test for name identification in RST generation
TST avoid nose running setup() in gen_rst.py
TST add sphinxext to testing
TST remove dependencies for testing sphinxext
Added Windows Powershell download script
ignificant refactoring, will now automatically install Python, pip, and nose. Numpy and Scipy still require manual intervention
Fixed bug with append string getting double "_py_py"
Added a unit test to ensure that there are no spurious repeating values in the thresholds returned by roc_curve because of machine precision, and a quick stab at a fix.
Changed to using wheel packages for scipy and numpy, currently hosted on the sklearn Rackspace account.
Slightly expanded the docstring for the test_roc_nonrepeating_thresholds test. Added named slice variables to same, for readability.
Improved the treatment of the machine precision issue for calculating ROC thresholds. Added a comment explaining why the treatment is needed.
Additional functions, ensuring pip is correct for python 3 and passing the proper path
Registry reloading is necessary the very first time Python is installed!
Fixed PATH issues for initial Python install environment
hange directory to $PYTHONHOME to avoid encodings error
hanging directories is *not* useful for the encoding error
Added longer delay after python silent install
dded verbose output when setting temporarily paths
Minor refactoring of the repeated-roc-thresholds test, for clarity.