Enable Downloading Wheels by Default

* Switches the default in pip.index.PackageFinder to True
* Supresses --use-wheel
* Adds --no-use-wheel which prevents the use of Wheel
upgrade setuptools
Setuptools 0.6 needs --no-use-wheel
REmove problematic tests that test dead simple functionality
Remove --use-wheel from the docs
Fix the flag name
Revert "REmove problematic tests that test dead simple functionality"

This reverts commit 0f4477000c92bd84e35ac411818e9161dc8ce217.
Fix the tests
Merge pull request #1302 from dstufft/turn-wheel-on-by-default

Enable Downloading Wheels by Default
use default theme, so we can evolve with RTD's design efforts.
Merge pull request #1312 from pypa/docs_rtd

use default theme, so we can evolve with RTD's design efforts.
Use the new name
better detection of docs theme
- if installing directly from a wheel, fail if it has an invalid name or is unsupported
- when walking links, skip invalid wheel filenames, don't crash