Updated config system

Moved configuration on to SeoObjectExtension to be more in line with
other modules, and made SEO tab show for all page types by default
Reinstate google suggestions
Fixed preview not always loading

The google search result preview would not always load the first time,
requiring the meta description field to be edited to trigger population.
Added save notice
Made GoogleSuggestField client-side only

This can mean a big performance improvement for websites hosted on
slower servers
Merge pull request #10 from jonom/master

Config update + extras