Make start and end of day changeable via property and scale it dynamically

[hendriku]

Currently the implementation only works with 7am to 7pm time values. after #5 has finished we should care of a dynamic sizing based of the earliest and latest events of the week. First step is to make the borders changeable programmatically via properties for the week component and afterwards set these properties dynamically. Id suggest to set the start always -1 hour of the earliest event and set the end +1 hour to the latest event.