added netstandard1.1 support

Author: Raul Hidalgo Caballero

src/GraphQL.Client/GraphQL.Client.csproj

@@ -9,7 +9,7 @@
 	</PropertyGroup>
 
 	<PropertyGroup>
-		<TargetFrameworks>netstandard1.3;netstandard2.0</TargetFrameworks>
+		<TargetFrameworks>netstandard1.1;netstandard1.3;netstandard2.0</TargetFrameworks>
 	</PropertyGroup>
 
 	<ItemGroup>
@@ -20,4 +20,8 @@
 		<ProjectReference Include="..\GraphQL.Common\GraphQL.Common.csproj" />
 	</ItemGroup>
 
+	<ItemGroup Condition="'$(TargetFramework)' == 'netstandard1.1'">
+		<PackageReference Include="System.Net.Http" Version="4.3.3" />
+	</ItemGroup>
+
 </Project>

src/GraphQL.Client/GraphQLClientExtensions.cs

@@ -116,6 +116,8 @@ public static async Task<GraphQLResponse> GetIntrospectionQueryAsync(this GraphQ
 		public static async Task<GraphQLResponse> PostIntrospectionQueryAsync(this GraphQLClient graphQLClient) =>
 			await graphQLClient.PostAsync(IntrospectionQuery).ConfigureAwait(false);
 
+		#if !NETSTANDARD1_1
+
 		/// <summary>
 		/// Send the Query defined in a file via GET
 		/// </summary>
@@ -134,6 +136,8 @@ public static async Task<GraphQLResponse> GetFromFile(this GraphQLClient graphQL
 		public static async Task<GraphQLResponse> PostFromFile(this GraphQLClient graphQLClient, string filePath) =>
 			await graphQLClient.PostQueryAsync(File.ReadAllText(filePath)).ConfigureAwait(false);
 
+		#endif
+
 	}
 
 }