Changing name of country table to countries
Merge branch 'dev' into dev-db
renaming 'country' table to countries' and adding function to Db to convert country names to codes.
Manually updating versions.
Adding checks to prevent instantiating Versions class when nZEDb_VERSIONS isn't defined.

Conflicts:
	nzedb/Sites.php
Fixing property name for Sites::version()
Merge pull request #451 from nZEDb/dev

Dev