Day streak is misaligned with users time zone

[rak3rman]

The streak algorithm doesn't seem to be aligned with the users time zone. For example, for me (a PDT user), the streak seems to be lost around midday (12-3pm) instead of at midnight. Take a look through the algorithm and make sure it is working as expected. There's a chance this issue may be blocked by the inclusion of the support for multiple users.