Leave:
#    -
#        employee: 1
#        covered_by: 2
#        starts_at: '2013-11-08'
#        ends_at: '2013-11-08'
#    -
#        employee: 6
#        covered_by: 3
#        starts_at: '2013-11-11'
#        ends_at: '2013-11-25'
#    -
#        employee: 4
#        covered_by: 6
#        starts_at: '2013-11-21'
#        ends_at: '2013-12-03'
    -
        employee: 5
        covered_by: ~
        starts_at: '2013-12-23'
        ends_at: '2014-01-07'

Leave:
    -
        employee: 1
        covered_by: 2
        starts_at: '2013-11-08'
        ends_at: '2013-11-08'
    -
        employee: 6
        covered_by: 3
        starts_at: '2013-11-11'
        ends_at: '2013-11-25'
    -
        employee: 4
        covered_by: 6
        starts_at: '2013-11-21'
        ends_at: '2013-12-03'
    -
        employee: 5
        covered_by: ~
        starts_at: '2013-12-23'
        ends_at: '2014-01-07'

Add cache for free days
Add cache for free days
