v15.0.0-preview-20170123-02

Fixes part of this release:

• Allow multiple test properties with same key #239, #358
• Localization for testplatform vsix package #146
• Working directory should be set to test source parent directory #311
• Allow relative source paths to vstest.console #331
• Stacktrace and error message should be in context of failed test #285

See release notes here