Editable locations: simplify database structure

This task is part of a bigger project focused on creating an interface for adding/removing/editing locations and taking care of db structure in order to achieve this.

This patch refactors the location table to a simpler (wid, name, serialized values) structure.
In the install file, it removes t() wraps around countries: translation should happen after data is fetched from db, not when it's inserted.
It also moves the location list into a function by itself, useful in case we need to load these locations again (for example, if we want to be able to restore a location to its defaults).