Change time selection for Reports

[astridschneider]

Let's change the way we select time ranges for the reports.

1. Dropdown for selecting Day - Week - Month - Year. Default selection Week.
2. Arrows pointing left and right < > for switching to the next/previous day/week/month/year
3. Date field showing the currently visible time range. Default: current week.
4. Checkbox called "Custom", when checked the date field becomes clickable and the user can customize the time range. "Search" button only in calendar popup.