Fixes bug where double/triple taps always True on Windows

touch.is_double_tap and touch.is_triple_tap are always True
on Windows even if the second/third tap is outside the
double/triple tap time. Fixes #1298.
Merge branch 'master' of https://github.com/kivy/kivy into windows_tap
Merge pull request #1348 from dkmadigan/windows_tap

Windows Double/Triple Tap Fixes #1298