#2287 pip is no longer relocatable Changes Pip to use -m pip or -c 'import pip; pip.main()' instead of using files that may not execute correctly. Changes InterpretersNode to use Pip.List instead of Freeze, so that all packages are displayed. Removes pip entry and directory list fallback from Pip.Freeze to allow it to correctly represent the contents of a requirements file. Updates CannotUninstall packages to include wsgiref (which is in the standard library but incorrectly appears in pip list for some versions) and to allow virtualenv and distribute to be uninstalled. Merges improvements to ProcessOutput from NTVS.
#2287 pip is no longer relocatable
Changes Pip to use -m pip or -c 'import pip; pip.main()' instead of using files that may not execute correctly.
Changes InterpretersNode to use Pip.List instead of Freeze, so that all packages are displayed.
Removes pip entry and directory list fallback from Pip.Freeze to allow it to correctly represent the contents of a requirements file.
Updates CannotUninstall packages to include wsgiref (which is in the standard library but incorrectly appears in pip list for some versions) and to allow virtualenv and distribute to be uninstalled.
Merges improvements to ProcessOutput from NTVS.

mousetraps/xtvs-common,mousetraps/xtvs-common,Microsoft/VisualStudio-SharedProject,enricosada/VisualStudio-SharedProject