Fixing error with SadSDK, and USBLib

The problem was that in this new repository, USBLib wasn't part of the git file structure, since our gitignore is set to ignore .dll files. In creating a new git repo, it got ignored. To solve the problem, I used `git add -f usblib.dll`
Added file selection dialog

Now you can select a target file oh-so-easily. Click the button, select the file, done!
Merge pull request #1 from lelandbatey/master

Added button to load targetfiles (and included usblib.dll)