Added cache clearing method to clear AFImageCache.
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/rcha/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking
Merge branch 'master' of https://github.com/AFNetworking/AFNetworking