#53 as_ical methods need to allow data order

[Shane Landrum]

See my comment at the end of Freebusy.pm.
Essentially, the RFC requires that we be able to
specify some order in our output, which we currently
can't do.

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Food for thought, from RFC2445 4.6.4:

When present in a "VFREEBUSY" calendar component,

the "DTSTART" and

"DTEND" properties SHOULD be specified prior to any

"FREEBUSY"

properties. In a free time request, these

properties can be used in

combination with the "DURATION" property to

represent a request for a

duration of free time within a specified window of

time.

as_ical methods currently don't let us specify the

output order. They'll

need to in order for us to be RFC-compliant here.

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