Merge source code from aspnet/DataProtection

src/DataProtection/DataProtection.sln

src/DataProtection/Directory.Build.props

src/DataProtection/Provision-AutoGenKeys.ps1

src/DataProtection/README.md

src/DataProtection/dependencies.props

src/DataProtection/samples/AzureBlob/AzureBlob.csproj

src/DataProtection/samples/AzureBlob/Program.cs

...DataProtection/samples/AzureKeyVault/AzureKeyVault.csproj

src/DataProtection/samples/AzureKeyVault/Program.cs

src/DataProtection/samples/AzureKeyVault/settings.json

.../samples/CustomEncryptorSample/CustomBuilderExtensions.cs

...amples/CustomEncryptorSample/CustomEncryptorSample.csproj

...ction/samples/CustomEncryptorSample/CustomXmlDecryptor.cs

...ction/samples/CustomEncryptorSample/CustomXmlEncryptor.cs

src/DataProtection/samples/CustomEncryptorSample/Program.cs

...on/samples/KeyManagementSample/KeyManagementSample.csproj

src/DataProtection/samples/KeyManagementSample/Program.cs

src/DataProtection/samples/NonDISample/NonDISample.csproj

src/DataProtection/samples/NonDISample/Program.cs

src/DataProtection/samples/Redis/Program.cs