Removing imports from src projects

src/Microsoft.AspNetCore.Server.WebListener/project.json

@@ -22,7 +22,6 @@
         "System.Security.Claims": "4.0.1-*"
       },
       "imports": [
-        "dotnet5.4",
         "portable-net451+win8"
       ]
     }

src/Microsoft.Net.Http.Server/project.json

@@ -17,7 +17,9 @@
   "frameworks": {
     "net451": {
       "frameworkAssemblies": {
-        "System.Runtime": { "type": "build" }
+        "System.Runtime": {
+          "type": "build"
+        }
       }
     },
     "netstandard1.3": {
@@ -37,10 +39,7 @@
         "System.Text.Encoding.Extensions": "4.0.11-*",
         "System.Threading": "4.0.11-*",
         "System.Threading.Overlapped": "4.0.1-*"
-      },
-      "imports": [
-        "dotnet5.4"
-      ]
+      }
     }
   }
 }

src/Microsoft.Net.WebSockets.Server/project.json

@@ -27,10 +27,7 @@
         "System.Threading.Tasks": "4.0.11-*",
         "System.Threading.Timer": "4.0.1-*",
         "System.Threading.ThreadPool": "4.0.10-*"
-      },
-      "imports": [
-        "dotnet5.4"
-      ]
+      }
     }
   }
 }