Fixed issue causing expression parsing of constant value expressions to fall through to default after parsing sets and arrays
Added a check when obtaining permanent object IDs to see if the object ID for an object is already permanent so an additional permanent ID is not generated
Added support for key path expressions disguised as function expressions. This allows for fetch requests with predicates including 'SELF.<keyPath>'.
Project cleanup.
Update readme
Merge pull request #2 from r-peck/master

Minor fixes to expression parsing and object ID generation