Keyboard: Don't convert keynames type to `future.types.newstr` on Python 2
Keyboard: Don't convert keynames type to `future.types.newstr` on Python 2

Instead it will be `unicode` on Python 2 and `str` on Python 3, avoiding
leaking details about python-future to our users.

stb-tester/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester