Target dotnet TFM's for class libraries

- Target `net451` and `dotnet5.4`
- Add SPA services project to solution (with .xproj)
- Add NuGet.config
- Update .gitignore

Microsoft.AspNet.ReactServices/project.json

@@ -1,20 +1,21 @@
 {
   "version": "1.0.0-alpha7",
-  "description": "Microsoft.AspNet.ReactServices Class Library",
-  "authors": [
-    "Microsoft"
-  ],
-  "tags": [
-    ""
-  ],
-  "projectUrl": "",
-  "licenseUrl": "",
+  "description": "ASP.NET 5 server-side React services,",
+  "repository": {
+    "type": "git",
+    "url": "git://github.com/aspnet/nodeservices"
+  },
   "tooling": {
     "defaultNamespace": "Microsoft.AspNet.ReactServices"
   },
+  "dependencies": {
+    "Microsoft.AspNet.Mvc.TagHelpers": "6.0.0-rc1-final",
+    "Microsoft.AspNet.NodeServices": "1.0.0-alpha7",
+    "Microsoft.AspNet.SpaServices": "1.0.0-alpha7"
+  },
   "frameworks": {
-    "dnx451": {},
-    "dnxcore50": {
+    "net451": { },
+    "dotnet5.4": {
       "dependencies": {
         "Microsoft.CSharp": "4.0.1-beta-*",
         "System.Collections": "4.0.11-beta-*",
@@ -24,12 +25,7 @@
       }
     }
   },
-  "dependencies": {
-    "Microsoft.AspNet.NodeServices": "1.0.0-alpha7",
-    "Microsoft.AspNet.Mvc.TagHelpers": "6.0.0-rc1-*",
-    "Microsoft.AspNet.SpaServices": "1.0.0-alpha7"
-  },
   "resource": [
     "Content/**/*"
   ]
-}
+}