Assume versions are a pre-release if we cannot parse them

* The most likely unparseable version is something like "dev" or
  "py6-dev" etc. The number of sane version numbers that are
  not normalizable and should be conisdered stable are fairly low.
Merge pull request #908 from pypa/dstufft/default-prerelease-true

Assume versions are a pre-release if we cannot parse them
update the release process
add link to pypa-dev list
Display hashdigest instead of hash object upon failure.
PreviousBuildDirError logging and test fix
PreviousBuildDirError test fix
Merge pull request #922 from qwcode/test_logging_consumer

PreviousBuildDirError test fix
wheel finder priority based on supported_tags order
remove old code from wheel test
Merge pull request #882 from qwcode/wheel_priority

wheel finder priority based on the order of the pep425 supported tags
add missing PermissionError import
add note about quoting requirement specifiers
quote our examples that use > or <
short test cache path segments to undercut windows path length
don't install or build wheels for distribute in python3
Merge pull request #937 from qwcode/ignore_reqs

don't install or build wheels for distribute in python 3
Added a pypip.in badge with the latest version.
write pip delete marker into global build dir upon creation
Merge pull request #948 from qwcode/global_build_cleanup

write pip delete marker into global build dir upon creation