Corrected ext in the Query intialize to return the proper string

The Query spec test was failing because the ext property was returning
'marketplace' instead of 'Id' so the matcher for 'MarketplaceIdList.Id.1'
would never pass.
merged FrancisGX master
Merge remote-tracking branch 'upstream/master'
Corrected Query to deal with multiple markets

According to the Amazon MWS specification, multiple marketplace ids are
listed as MarketplaceId.Id.1,MarketplaceId.Id.2,etc. and not
MarketplaceIdList.Id.1, MarketplaceIdList.Id.2, etc.
Merge pull request #2 from rnhurt/master

Corrected Query to deal with multiple market ids