Adding testRunner to enable tests

test/Microsoft.AspNetCore.SignalR.SqlServer.Tests/project.json

@@ -13,7 +13,5 @@
   "frameworks": {
     "dnx451": {}
   },
-  "commands": {
-    "test": "xunit.runner.aspnet"
-  }
+  "testRunner": "xunit"
 }