fix(store): properly hide hidden keys from watchers, not just gets
fix(store): move logic to handle whether or not to notify (re: hidden keys) entirely into watcher hub
test(store): exercise watchers receiving notifications of non-hidden keys within hidden directories
fix(store): make isHidden see if any portion of the path is hidden, not just the last element
test(store): group together all store tests that deal with hidden keys
Merge pull request #498 from tobz/actually-hidden-keys

fix(store): properly hide hidden keys from watchers, not just gets