ENH: tool to DL release wheels from Anaconda
ENH: tool to DL release wheels from Anaconda

* because of the rackspace -> `anaconda.org` migration
for binary assets during the release process, we should
probably "borrow" the approach NumPy is using to retrieve
wheels from the new site--see:
https://github.com/numpy/numpy/pull/16265

* I modified the NumPy script only to account for the
name change to SciPy in a few places

* testing locally, it seems to work ok--I may need to
first purge the staging area of all the merged/uploaded
"junk" binaries before the release though, since there's
a bit of promiscuity otherwise:

```
mkdir wheelhouse
python tools/download-wheels.py 1.5.0 -w ./wheelhouse/
...
Downloading wheel 1, name:
scipy-1.5.0.dev0+01c65a7-cp37-cp37m-manylinux1_i686.whl
Downloading wheel 2, name:
scipy-1.5.0.dev0+01c65a7-cp36-cp36m-manylinux1_i686.whl
Downloading wheel 3, name:
scipy-1.5.0.dev0+01c65a7-cp38-cp38-manylinux1_i686.whl
Downloading wheel 4, name:
scipy-1.5.0.dev0+01c65a7-cp37-cp37m-manylinux1_x86_64.whl
```

rgommers/scipy,vigna/scipy,scipy/scipy,WarrenWeckesser/scipy,endolith/scipy,perimosocordiae/scipy,Eric89GXL/scipy,andyfaff/scipy,rgommers/scipy,vigna/scipy,rgommers/scipy,andyfaff/scipy,vigna/scipy,pizzathief/scipy,Eric89GXL/scipy,matthew-brett/scipy,WarrenWeckesser/scipy,nmayorov/scipy,Eric89GXL/scipy,scipy/scipy,ilayn/scipy,e-q/scipy,perimosocordiae/scipy,endolith/scipy,matthew-brett/scipy,scipy/scipy,e-q/scipy,pizzathief/scipy,andyfaff/scipy,ilayn/scipy,nmayorov/scipy,WarrenWeckesser/scipy,endolith/scipy,pizzathief/scipy,Stefan-Endres/scipy,andyfaff/scipy,grlee77/scipy,perimosocordiae/scipy,pizzathief/scipy,rgommers/scipy,zerothi/scipy,matthew-brett/scipy,Stefan-Endres/scipy,grlee77/scipy,anntzer/scipy,scipy/scipy,e-q/scipy,nmayorov/scipy,matthew-brett/scipy,grlee77/scipy,scipy/scipy,zerothi/scipy,anntzer/scipy,Stefan-Endres/scipy,Eric89GXL/scipy,andyfaff/scipy,endolith/scipy,anntzer/scipy,Stefan-Endres/scipy,nmayorov/scipy,zerothi/scipy,mdhaber/scipy,zerothi/scipy,vigna/scipy,e-q/scipy,anntzer/scipy,e-q/scipy,andyfaff/scipy,pizzathief/scipy,WarrenWeckesser/scipy,tylerjereddy/scipy,ilayn/scipy,vigna/scipy,endolith/scipy,zerothi/scipy,WarrenWeckesser/scipy,ilayn/scipy,mdhaber/scipy,tylerjereddy/scipy,Eric89GXL/scipy,perimosocordiae/scipy,zerothi/scipy,WarrenWeckesser/scipy,perimosocordiae/scipy,endolith/scipy,scipy/scipy,anntzer/scipy,matthew-brett/scipy,mdhaber/scipy,perimosocordiae/scipy,tylerjereddy/scipy,mdhaber/scipy,ilayn/scipy,tylerjereddy/scipy,Stefan-Endres/scipy,Stefan-Endres/scipy,rgommers/scipy,mdhaber/scipy,ilayn/scipy,mdhaber/scipy,grlee77/scipy,Eric89GXL/scipy,anntzer/scipy,nmayorov/scipy,grlee77/scipy,tylerjereddy/scipy