Pull in from Contacts and Vendors, add more fields from XML to post_meta

There are two commits here. One of them adds more fields from the XML field into the post_meta for each corresponding post. There is a also a tiny bug fix to post_meta imports where "latitude" was incorrectly spelled.

The second, larger commit adds new imports for Contacts and Vendors. Most people might not use this, but since the XML files are produced on Marcato's end and you can mark the objects as public/private within Marcato I don't think it would hurt to import them. We plan to use Contacts to drive our Bio page so people can edit their own photo/bio within Marcato and those pages/updates will sync with the website. We plan to use Vendors as a directory of restaurants and lodging, automatically driven by the data in Marcato for the Vendors we mark "Public".

I didn't bump the version number in the plugin or the Read Me. Since this adds a few larger features we may want to give it "1.4.0" or similar.