Adds test for keypaths
Merge branch 'master' into add_support_to_keypaths

* master:
  Covers [OPContainer initWithParams:]
Adds category on NSString to check if the receiver is a keypath
Adds sections on implementation
Adds method to return the root object if the receiver is a KeyPath
Dispatches setObject:forKeyPath: to support keypats
Adds rootKey and relativeKeyPath to NSString
Adds support for set and get values based on KeyPaths
Refactors how to obtain the root object for a keypath
Adds support for keypaths
Merge pull request #7 from vbergae/add_support_for_keypaths

Add support for keypaths