Add installation guide for Carthage
Add installation guide for Carthage

ninjaprox/NVActivityIndicatorView,ninjaprox/NVActivityIndicatorView,bwearley/NVActivityIndicatorView,bwearley/NVActivityIndicatorView,waterskier2007/NVActivityIndicatorView,ninjaprox/NVActivityIndicatorView,ninjaprox/NVActivityIndicatorView,waterskier2007/NVActivityIndicatorView