cmis properties mixed with object properties creates confusion

The piggy-backing of CMIS properties in the object properties makes for some inconvenient processing. When setting fields (in an entry), some of those fields also have to be pushed into the properties. And when reading the properties from an entry (say, to create or update a document), you must filter out all the cmis properties (since they don't match the set of allowed types for the document). It seems that since we have a cmis-specific schema (extending atom), we could create a set of specific fields for this data. Note that this piggy-backing also means that documents which have actual properties with names which collide with the CMIS names (such as "Uri" and "Name") will not be processed properly. There will either be an error against the CMIS spec (because for example Name got populated with the actual property from the repo) or an error in function (because the property Name doesn't come through in the entry document).