Bug 1060386 - Mobile Client needs to report the number of shared URLs on FxOS. r=jaoo

Whatever... :)
I honestly don't get the naming patterns of this app. We have `js/helpers` for some js files and `js` for others and then we have `libs` for other "helpers"... The concept of helper is quite broad, everything helps here :D.
In this case FeedbackClient is the client part of a remote service and MetricsHelper the base class of this client that isn't used directly and helps with things like persistent storage, retries, etc.