Update _clientwindow.py

Fixed "1v1 player searching" notification grammar error.
Merge pull request #74 from AThorley/develop

Update _clientwindow.py
Merge branches 'develop' and 'feature/new-patcher' of https://github.com/FAForever/lobby into feature/new-patcher
Fix for a refactoring bug
Accelerated and implemented some unit tests.
Added unit tests for patching, mismatches, and untouched files.