Added projectUserMinutesAction

This retrieves the minutes booked in a specific time separated by
project and users
Also send the project title and user name in projectUserMinutesAction
Added getProjectUserMinutes to the timecard client model
Move the buttons below the header, just above the table/graph

This emphasizes that they belong to the graph only.
Added projectUserTimeTable to the statistics page
Use the zend context switching helper to deliver json

This will allow us to add csv later.
Zend doesn't allow setting a default context, so we just set the format
parameter if it's not provided by the client to do that.
Generate the json in a view.

We mustn't deactivate the view renderer and convert to json in a view script to
use the contexts for other formats
Add a csv context.

Now ?format=csv will result in a csv download.
This commit includes a view script to convert to csv.
Moved time select box to own widget
use timehelper instead of time
use a single line per import
move the time regexp to the timehelper
Parse the time regexp in the timehelper

This removes all other places of the regexp
added an export form to the statistics page
remove debugger;
Call it timeRegexpString to make clear its not a real regexp
wrap the anonymous function in parentheses
Added IndexController->getDateParam(...) to validate isodates

This will throw an Phprojekt_Exception_InvalidParameter if the parameter is
malformatted.
use _getDateParam to validate isodate parameters
simplify regexp a little