Report SDK version mismatches

[studioph]

I was recently helping a user on Nexus troubleshoot a situation where adding one of my patchers was causing just Blocking Error with no message. After looking at their logs, the issue was they were running an older version of the .NET SDK than what was required. It would be a good idea from a UX perspective to catch this and display to the user so they know they need to upgrade their SDK install.

More details in studioph/QuestsAreInSkyrimPatcher#2

I would be happy to implement this, just wanted to put something out there in case others happen to run into this weird scenario (and so I don't forget).