If there is no gravatar use an identicon instead of 404ing.

Removes an unnecessary reference to WPAvatarSource
Updating WordPressApi pod
Fixes static analyzer warnings. Part 1
Adds missing semiconlon
Fixes static analyzer warnings. Part 2
Fixes static analyzer warnings. Part 3
Fixes static analyzer warnings. Part 4
Adds missing pointer dereference
Fixes unread assignment warning
Adds missing assignment
Fixes memory leak
Merge pull request #1709 from wordpress-mobile/issue/1706-fixes-analyzer-warnings

Issue #1706: Fixing Static Analyzer Warnings
Merge pull request #1705 from wordpress-mobile/issues/1626-update-wordpressapi-pod

Updating WordPressApi pod
Merge pull request #1690 from wordpress-mobile/issues/1664-use-identicons

If there is no gravatar use an identicon instead of 404ing.
Merged develop -> issue/1618-AFNetworking2.