Update AppVeyor builds

[jason-roberts]

• .NET Core tests being executed
• .NET Full tests being executed
• UWP tests being executed

[jason-roberts]

Need to look at UWP command line tests in AppVeyor
For example

vstest.console.exe "D:\dev\FeatureToggle\src\Tests\FeatureToggle.UAP.Tests\AppPackages\FeatureToggle.UAP.Tests_1.0.1.0_x86_Debug_Test\FeatureToggle.UAP.Tests_1.0.1.0_x86_Debug.appx"

Errors with:

C:\Program Files (x86)\Microsoft Visual Studio\2017\Enterprise>vstest.console.exe "D:\dev\FeatureToggle\src\Tests\FeatureToggle.UAP.Tests\AppPackages\FeatureToggle.UAP.Tests_1.0.1.0_x86_Debug_Test\FeatureToggle.UAP.Tests_1.0.1.0_x86_Debug.appx"
Microsoft (R) Test Execution Command Line Tool Version 15.0.26228.0
Copyright (c) Microsoft Corporation. All rights reserved.

Starting test execution, please wait...
Warning: Using Isolation mode to run unit tests for Windows Store apps. Use the /InIsolation parameter to suppress this warning.
Error: Installation of package 'D:\dev\FeatureToggle\src\Tests\FeatureToggle.UAP.Tests\AppPackages\FeatureToggle.UAP.Tests_1.0.1.0_x86_Debug_Test\FeatureToggle.UAP.Tests_1.0.1.0_x86_Debug.appx' failed with Error: (0x800B0109) A certificate chain processed, but terminated in a root certificate which is not trusted by the trust provider.

error 0x800B0109: The root certificate of the signature in the app package or bundle must be trusted..
For more details look into Event Viewer under Applications and Services Logs -> Microsoft -> Windows -> AppXDeployment-Server -> Microsoft-Windows-AppXDeploymentServer/Operational.

Look like need to:

• Make appx package be generated automatically as part of build
• Get correct command line options for vstest.console.exe
• Certificate shenanigans - see: http://stackoverflow.com/questions/33771590/running-universal-windows-unit-tests-from-the-command-line