Rename blog Ids in the blog model, to clear up what they should be used for. Refs #607.

Blog.id becomes Blog.localTableBlogId.
Blog.blogId becomes Blog.remoteBlogId.
Change Media to use localTableBlogId instead of remoteBlogId. Fixes issue where you could see media for other self-hosted blogs added to the app. Refs #607.
Renamed getCurrentBlogId() and getCurrentBlogAccountId() to match the new naming conventions. I noticed that the remoteBlogId was being passed to CommentDetailFragment, which didn’t seem necessary so I made a few changes to use the localTableBlogId instead.
Clarified the use of local vs. remote blogId in comment detail
Merge pull request #623 from wordpress-mobile/issue/607-rename-blog-id

Rename blog Ids in the blog model, to clear up what they should be used ...