Samples for Batch API (#941)

* Batch API Sample

* Dispose BatchResponse consistently for simplicity

* More polish to sample

* Minor typos

* Minor cleanup bug

* Unexpected error handling; minor tweaks

* Dispose the streams

* Use SDK v3.4

Microsoft.Azure.Cosmos.Samples/Usage/Batch/Batch.csproj

@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <AssemblyName>Cosmos.Samples.Batch</AssemblyName>
+    <RootNamespace>Cosmos.Samples.Batch</RootNamespace>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Configuration" Version="2.2.0" />
+    <PackageReference Include="Microsoft.Extensions.Configuration.FileExtensions" Version="2.2.0" />
+    <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="2.2.0" />
+    <PackageReference Include="Newtonsoft.Json" Version="12.0.2" />
+    <PackageReference Include="Microsoft.Azure.Cosmos" Version="3.4" />
+  </ItemGroup>
+  <ItemGroup>
+    <None Include="..\AppSettings.json">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+  </ItemGroup>
+</Project>