[Chandler-dev] 0.7 backwards compatibility with 0.6 shared collections

[Morgen Sagen]

Although it wasn't an explicit requirement to have 0.7 clients be  
able to share with 0.6 clients, there have only been a few schema  
changes that have affected backwards compatiblity:

1) The switch to non-naive datetimes
2) The change of the 'body' attribute
3) The change from InclusionExclusionCollection to SmartCollection

...and so I've been putting in small workarounds to keep sharing  
backwards compatible.  Today I added back  
InclusionExclusionCollection (simply a subclass of SmartCollection).

All the places in the code I have 0.6 compatibility workarounds are  
marked with:

# @@@MOR 0.6 sharing compatibility

When we discuss the sharing format in a couple weeks, we can address  
long term solutions for this, and remove these three workarounds.

~morgen