Bug 986095 - Part 1: Track session for Reader viewer r=rnewman,liuche
Bug 986095 - Part 2: Track sharing article from Reader viewer r=rnewman
Bug 986095 - Part 3: Track adding article to Reading List r=liuche
Bug 986095 - Part 4: Add JS Sessions and Events into TelemetryContract.java r=rnewman
Bug 986095 - Part 5: Don't log missing Session on stopUISession r=rnewman