Close #25
Small logging tweak
The top X tickets now properly listens to queues (when selected).
The widget "Open Tickets" now listens to the queues you select on a Dashboard.
These changes fix the tickets by source widget. It properly filters the data
based on any selected queues.
This SQL addition is needed for the widgets to filter by queue ID's properly.
Now the standard ticket status widgets listen to the queues like they should as well.
Small patch that removes cache more agressively. Could solve the issue
with the rearrangement of widgets - at least on my dev. it was solved.
A few variables renamed.
Renamed a few variables
These changes have been made for issue #40.

It doesn't change anything in the way data is fetched from the API, it only
changes the way worked and billable hours are calculated.
These changes hopefully make it easier to debug the issue described in #40

They allow you to run the cronjob while focusing on a single type of data:
- open_tickets
- completed_tickets
- time_entries

Run the cronjob with

```
-d time_entries
```

to only handle the time entries.
This change:
- Makes optional output only show up when using the -d option (instead of always)
- Contains a possible fix for the ticket by source issue mentioned in #31
- Extends the -d option with choice "ticket_sources"
Fixes #27
The tickets by source just kept acting freaky. Rebuilt the logic.
If you added a new source, you would be missing history and your graph would crash.
That has been resolved now.
Slight pimp to the "open tickets" widget, didn't align properly.