Fix Issue 4
* Added in library for signing the generated RDP file
* Library requires the certificate to have a friendly name for it to show up in the drop down. No friendly name, no certificate in dropdown
* Library detects the rdpsign.exe version to determine proper arguments (/sha1 or /sha256)
* Updated RemoteApp Tool to use new library and sign the RDP file after it is created
* Added in logic around the signing to prevent editing after creating the RDP file if signed
* Library allows for creating an unsigned backup along with the signed version, added ability to do the same in RemoteApp Tool
* Updated RemoteApp tool to use Visual Studio 2019, but allows for support back to some pervious versions
* Tested on Windows 10 and Windows Server 2008 R2 and was successful on both