Merge branch 'release/v0.20.0-rc1'
Merge branch 'master' of git://github.com/RestKit/RestKit into development
Modify RestKit to support Dropcam API with forcePluckObjectFromCollectionMapping and ignoreKeyPathAttributeMapping

RKMapping - Add two new booleans, forcePluckObjectFromCollectionMapping and ignoreKeyPathAttributeMapping, that causes object mapping to occur in specific fashions. forcePluckObjectFromCollection will try to use the first element of a collection as the mappable JSON instead of the collection itself given a root key path. ignoreKeyPathAttributeMapping, when enabled, causes object mapping to ignore the key path implications of property names with periods in them. Instead, objects will be serialized with property names that include a period.

RKMappingOperation - react to ignoreKeyPathAttributeMapping flag being set

RKMapperOperation - react to forcePluckObjectFromCollectionMapping flag being set