Masquerade: Retain parkinglot settings made by CHANNEL function.

Prior to this patch, the user would have a parkinglot set on a channel that
was parked and when the channel was retrieved, any attempt by that channel
to park would simply use the default. This patch makes parkinglot values
set in this way be retained through the masquerade.

(closes issue AST-990)
Reported by: Nick Huskinson
Patches:
    masquerade_parkinglot_patch.diff Uploaded by Jonathan Rose (license 6182)
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Merged revisions 372736 from http://svn.asterisk.org/svn/asterisk/branches/1.8
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Merged revisions 372737 from http://svn.asterisk.org/svn/asterisk/branches/10
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Merged revisions 372754 from http://svn.asterisk.org/svn/asterisk/branches/11


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@372755 65c4cc65-6c06-0410-ace0-fbb531ad65f3