Allow MvcRazorHost to run on vanilla .NET45

- Added net45 target and removed specific aspnet50 and aspnetcore50 APIs
from that code path.

src/Microsoft.AspNet.Mvc.Razor.Host/MvcRazorHost.cs

@@ -9,7 +9,10 @@ using Microsoft.AspNet.Razor;
 using Microsoft.AspNet.Razor.Generator;
 using Microsoft.AspNet.Razor.Generator.Compiler;
 using Microsoft.AspNet.Razor.Parser;
+
+#if ASPNET50 || ASPNETCORE50
 using Microsoft.Framework.Runtime;
+#endif
 
 namespace Microsoft.AspNet.Mvc.Razor
 {
@@ -36,6 +39,7 @@ namespace Microsoft.AspNet.Mvc.Razor
         // This field holds the type name without the generic decoration (MyBaseType)
         private readonly string _baseType;
 
+#if ASPNET50 || ASPNETCORE50
         /// <summary>
         /// Initializes a new instance of <see cref="MvcRazorHost"/> with the specified
         /// <param name="appEnvironment"/>.
@@ -45,6 +49,18 @@ namespace Microsoft.AspNet.Mvc.Razor
             : this(new PhysicalFileSystem(appEnvironment.ApplicationBasePath))
         {
         }
+#elif NET45
+        /// <summary>
+        /// Initializes a new instance of <see cref="MvcRazorHost"/> with the specified
+        /// <param name="root"/>.
+        /// </summary>
+        /// <param name="root">The path to the application base.</param>
+        public MvcRazorHost(string root) :
+            this(new PhysicalFileSystem(root))
+        {
+
+        }
+#endif
 
         /// <summary>
         /// Initializes a new instance of <see cref="MvcRazorHost"/> using the specified <paramref name="fileSystem"/>.

src/Microsoft.AspNet.Mvc.Razor.Host/project.json

@@ -6,11 +6,10 @@
   "dependencies": {
     "Microsoft.AspNet.FileSystems": "1.0.0-*",
     "Microsoft.AspNet.Mvc.Common": "",
-    "Microsoft.AspNet.Razor": "4.0.0-*",
+    "Microsoft.AspNet.Razor": "4.0.0-*"
-    "Microsoft.Framework.Runtime.Interfaces":  "1.0.0-*"
   },
   "frameworks": {
-    "aspnet50": {
+    "net45": {
       "dependencies": {
         "System.Collections": "",
         "System.Runtime": "",
@@ -18,6 +17,15 @@
         "System.Xml.Linq": ""
       }
     },
+    "aspnet50": {
+      "dependencies": {
+        "System.Collections": "",
+        "System.Runtime": "",
+        "System.Xml": "",
+        "System.Xml.Linq": "",
+        "Microsoft.Framework.Runtime.Interfaces": "1.0.0-*"
+      }
+    },
     "aspnetcore50": {
       "dependencies": {
         "System.Collections": "4.0.10.0",
@@ -36,7 +44,8 @@
         "System.Runtime": "4.0.20.0",
         "System.Runtime.Extensions": "4.0.10.0",
         "System.Runtime.InteropServices": "4.0.20.0",
-        "System.Threading.Tasks": "4.0.10.0"
+        "System.Threading.Tasks": "4.0.10.0",
+        "Microsoft.Framework.Runtime.Interfaces": "1.0.0-*"
       }
     }
   }