Copy the below xml into the file mentioned above and reinstall GAX. That worked for me... Of course, make a copy of the current file.
<?xml version="1.0" encoding="utf-8"?>
<RecipeFramework SchemaVersion="1.0" TraceLevel="Error" xmlns="http://schemas.microsoft.com/pag/gax-manifest">
<Hosts>
<Host Name="VisualStudio" InstallerType="Microsoft.Practices.RecipeFramework.VisualStudio.RecipeFrameworkInstaller, Microsoft.Practices.RecipeFramework.VisualStudio" />
</Hosts>
<GuidancePackages>
</GuidancePackages>
</RecipeFramework>