Support Async SoapClient/NVPClient

[gwilliams]

• Upgraded projects to target .Net framework 4.6 - Seriously out of date here
  • Had to upgrade to 4.6 in order to get the async task based WCF support
• Added async task based support to the SoapClient and NVPClient
  • Re-added the service references with Task based async support, targetting 1.147
  • Sync methods call the Async methods internally and wait for the .Result to finish
• Tidied up a bit of naming conventions (can be undone, but it was screaming out to be completed) and code formatting
• Updated the SoapSample application to allow it to run either Sync of Async (but with blocking unfortunately)

[gwilliams]

Not 100% sure why the build failed with errors relating to not being able to find AssemblyInfo.cs in all 3 sample applications.