WPRichTextView: Invalidating content size on the main thread
Adds/restores missing share activity images.
Merge pull request #1954 from wordpress-mobile/issues/1911-missing-share-activity-icon

Adds/restores missing share activity images.
Merge pull request #1952 from wordpress-mobile/issues/1951-dtcoretext-crash

WPRichTextView: Invalidating content size on the main thread
Implement restoration for StatsViewController

The WPStatsViewController class already implemented view controller
restoration, but the subclass didn't.

When a StatsViewController was restored, `self.blog` was `nil`, which
would cause it to prompt to install Jetpack, as `[nil hasJetpack]`
evaluates to false.

Fixes #1958
Add missing braces
Merge pull request #1964 from wordpress-mobile/issue/1958-jetpack-prompt-after-force-close

Implement restoration for StatsViewController
Merge branch 'release/4.2' into issue/1959-jetpack-login

Conflicts:
	WordPress/Classes/ViewRelated/Stats/StatsViewController.m