Ignore .xccheckout file

Xcode 6 started to generate this file which seems to
be user specific. Therefore, it doesn't need to be checked
into Git.
Provide a way to get shared instance of object configurator
Fully configure a FeedManager instance
Configure feed list view controller and its dependencies
Move FeedManagerDelegate protocol conformance to .h file

We need this conformance to be visible in order to set the
feed list view controller as a delegate to FeedManager in
ObjectConfigurator.
Merge pull request #4 from pawanpoudel/features/dependency_injection

Create a light-weight dependency injection framework