Blog preview waits until blogInfo is loaded before showing/updating posts in the current blog - this ensures we have a blogId before updating
Updated ReaderSubsActivity to retrieve a blog's site ID after user enters a URL to follow, then using that ID when following the blog.
Merge pull request #1874 from wordpress-mobile/issue/1872-reader-empty-blog-preview

issue/1872-reader-empty-blog-preview
Merge branch 'develop' of https://github.com/wordpress-mobile/WordPress-Android into feature/reader-comment-activity