adds 'BW::NetworkIndicator'
updated README
don't need this block
models the spinner behavior after AFNetworking; hiding the spinner is delayed (avoids flickering), thread support (all updates are on the main thread)
include 'network-indicator' as part of 'http'
only alloy one 'error'
geez, that took a lot of 'cancel's!
don't need this to be outside lambda
fixes for osx
Merge pull request #349 from colinta/network_indicator

adds 'BW::NetworkIndicator'