A bunch of small changes

After the speed of the hackathon last week, I took some time for polishing up a few things. No need to dive in into details, here's the list.

Bug fixes

1. Some of you received emails that your streak was at risk even though it wasn't or even though you weren't subscribed to emails. Sorry about that. I made a logic mistake in that feature. All should be good now.

Improvements

1. I've clean up the way we send notifications. This means that your daily digest and email notifications are more useful (includes links to the pages that your notifications are about). You can edit your notification preferences in your account settings.

2. If you forget to submit your daily exercise during the review step, it will be submitted at the end of the day regardless so your streak does not break.

3. When writing comments on the ideas board, pressing enter no longer submits the message. This is now consistent with comments on stories.