AFIncrementalstore Changes
Fixes backwards notifications for values and relationship notifications.
Post notification for AFIncrementalStoreContextWillFetchNewValuesForRelationship.
Refresh destination object when an insert fails, prevent dangling relationships.
Don't try to insert a nil object to the array.
Skip relationships that are fault when updating backing object with managed object

We can safely assume relationships that are fault were not modified
AFINcrementalStore changes
Merge pull request #223 from baarde/skip_fault_relationships_update

Skip relationships that are fault when updating backing object with managed object
Merge pull request #221 from Spaceman-Labs/bugs/dangling_relationship

Prevent dangling relationships when an insert save fails
Minor refactoring
Merge pull request #220 from Spaceman-Labs/bugs/notifications

Fix reversed context notifications
[Issue #217] Using backing object ID cache
Merge branch 'master' of https://github.com/AFNetworking/AFIncrementalStore
User datasource updates
[Issue #212] Reverting to use of constant value for incremental node, rather than absolute time
reverted version
merge from upstream/master
Message sending and liking changes
Profile and registration fixes