Simplify Attendance and Punctuality

The existing written policy of "flextime" is uncessarily strict. We want
people to attend standup and to otherwise keep a pretty regular schedule,
communication with the operations team and their team about their schedule.

These changes hopewfully reflect that.
Agreed that:

* It would be good to mention the project standup. Standups are more useful when everyone is there.
* It's worth mentioning that you're expected to be in the office by standup so that you can attend.