Change Microsoft.DotNet.Web.Spa.ProjectTemplates to use 1.0.0-preview-* version numbers since the first release will be 1.0.0

Author: SteveSandersonMS

templates/package-builder/src/dotnetnew/Microsoft.DotNet.Web.Spa.ProjectTemplates.nuspec

@@ -2,7 +2,7 @@
 <package xmlns="http://schemas.microsoft.com/packaging/2010/07/nuspec.xsd">
     <metadata>
         <id>Microsoft.DotNet.Web.Spa.ProjectTemplates</id>
-        <version>2.0.0-preview2-{buildnumber}</version>
+        <version>1.0.0-preview-{buildnumber}</version>
         <description>Single Page Application templates for ASP.NET Core</description>
         <authors>Microsoft</authors>
         <language>en-US</language>