Solution: Adjust solution file after migrator rename/move

Since the migrator was moved, then renamed in master, which was merged back, and then renamed and moved again, the solution is out of date.

Update the solution file to point to the proper project files.
Installer: Repair project file

After the merge the project file of the installer was broken. Revert the file back to the previous state since the changes in it are not important for this branch.
.gitignore: Add .config files to ignore list

Remove all .config files from version control since the migrator tester may house several test files and it's convenient to not see these listed at time of commit.