Enable framework rollover in apphost without application config file

[Tyrrrz]

Details

Currently we use a .config file to enable framework rollover, so that the bootstrapper executable can run against .NET Framework v3.5 as well as .NET Framework v4.x.

https://github.com/Tyrrrz/DotnetRuntimeBootstrapper/blob/5e36f525ed981f5219c7245fb1d54f7d5a5fb9ec/DotnetRuntimeBootstrapper.Executable/App.config

It is also possible to achieve this without a manifest file, but requires considerably more effort. See here:

https://gist.github.com/MichalStrehovsky/d6bc5e4d459c23d0cf3bd17af9a1bcf5