Added initial iot-device-binding template

[shaggygi]

This is a first attempt at adding a new template project for IotDeviceBindingTemplate.

See #84 for more information as there are some future action items added.

To get started...

1. Download repo to local machine.
2. Run cmd below where XXX is the folder you downloaded repo.
   NOTE: This will be improved once a NuGet package is provided.

dotnet new -i "C:\XXX\tools\IotDeviceBindingTemplate\dotnet_new_iot-device-binding_csharp"

You should now be able to see the template installed at this point using dotnet new -l

3. You can now create a new binding by running cmd below where XXX is the location the binding structure will be created.

dotnet new iot-device-binding -o C:\XXX\PioLed -n PioLed

The following structure will be created:

iot/
  src/
    devices/
      PioLed/
        PioLed.csproj
        PioLed.cs
        README.md
        samples/
          PioLed.Sample.csproj
          PioLed.Sample.cs
          README.md
        tests/   <--  Tests are optional (these can be deleted if not needed)
          PioLed.Tests.csproj
          PioLed.Tests.cs

4. Add and test your binding code.

NOTE: This PR only supports C#, but is hopefully structured to add VB and F# in a future PR.

[joperezr]

Thanks @shaggygi!