Add Share functionality when tapping the share button.

User's should see a UIActivityViewController with an "Open in Safari" option that should take the user to their Wikitext user talk page in Safari. (https://en.m.wikipedia.org/wiki/User_talk:Jkatz_(WMF))

We should also make sure the native screens refresh when the user returns to the app in case they made an update in Safari and expect to see a change when they return.