Merge pull request apple#173 from etschannen/release-5.1

Release 5.1.7

Merge pull request apple#162 from alecgrieser/configurable-venv-url

Make virtualenv download directories overridable

Merge pull request apple#143 from yichic/release-5.1.5

Create release 5.1.5

Updated to version 5.1.4

Merge pull request apple#50 from bnamasivayam/release-5.1

Add new guid for wxs

Release 5.1.2

Release 5.1.1

Release 5.1.0

Release 5.0.8

Release 5.0.7