Make sure options exist after activation

- Avoid extra db query if option doesn't exist
- Make sure the option as saved on activation will contain translated defaults
Merge branch 'master' into Small-fixes
Remove the extra blog name added to the title by woo_title()
Fixes #1308
Set rssafter to empty string on test_embed_rss() test
Check if get_queried_object_id is not 0 before enqueueing wp_enqueue_media
Change log update
Change log update & version increment
Added release date to change log
Removed extra linebreaks from changelog
Format unix timestamp to string in sitemap.
Fixes #1311
Merge branch 'master' of git://github.com/Yoast/wordpress-seo into Issue-1302