Add parameter assertions when initializing an RKResponseMapperOperation
Add new HTTP utilities for working with dates. Borrowed from SDURLCache
Add new optimization to permit RKObjectRequestOperation to avoid the network and use an existing cached response. Update initialization paths for RKObjectRequestOperation to work with requests instead of request operations.
Log full cached response headers at Trace log level for debugging caching
Drop deprecated URLEncodedString:
Merge branch 'feature/xcodeproject-householding' of https://github.com/diederich/RestKit into feature/reboot-networking-layer
Merge branch 'fix/mem-leak' of https://github.com/diederich/RestKit into feature/reboot-networking-layer
fix build of twitter sample

* new network activity indicator handling
* new object mapping interface
* new ResponseDescriptor interface
* new query interface
* init RKObjectManager with an AFHTTPClient instance
configure MIMEtype via AFHTTPClient

also remove non-working XML sample
Setup a default managedObjectCache instance of RKFetchRequestManagedObjectCache
Clean up issues instantiating managed vs unmanaged object request operations through the object manager.
Fix warnings about missing assign property declarations
Add license boilerplate
Add license boilerplate; rev docs
Merge Twitter example code fixes from mdd; closes #927
Add request and response descriptors to Network.h
Add support for no-cache header to require revalidation with the server. fixes #1465
Add support for creating an NSMutableURLRequest for a relationship
Use a reverse object enumerator when enumerating the fetch request blocks to allow blocks registered later to override earlier registrations
Atomize dependencies and make Search and Testing modules optional. Add RestKit/Core preferred dependency