Remove one month restriction on Leave requests

1. The longest Absence request possible is one month, but Maternity Absence in the UK can last as long as a full year. The restriction that the end date should be within a month of the leave start date should be removed.

2. It should be possible for a leave request to be made on any date of a month and end on any day of any other month. Currently it is only possible to request leave where the start and end date are both within the same month.