added convertDelta.  supports set/unset
convertDelta supports mapping
convert delta splits out remote paths and applies add/remove to them
CacheWriter applies deltas to cache
key selection limits cache operations
removed unused data
convertDelta only creates set/unset
CacheWriter/mock fixes
added CacheManager with integration tests
added extractKeys function
added code to convert a query to an idSet given the cache
CacheManager forwards get/find/follow methods to cache
convertToIdSet returns empty array when no results are found
added convertToValue to resolve the right side of query expressions
added 'box' to util
convertToIdSet internally uses convertToValue
fixed test
QueryWriter draft implementation
QueryWriter.ready responds correctly to empty idSet and undefined criteria
added extractDependencies