Bump auto-increment fields in database to a high and recognizable starting offset.

[dmsnell]

Preliminary work for #727

Let's rewrite every table create to shift the starting auto_increment value to something large and recognizable so that it's easier later to rewrite id values stored in the database.

For example, starting ids at 1,325,476,980 leaves 700 million ids (in a 32-bit Playground) and would make it easier to make a subjective call if some integer in the database is likely an id. This can be used to dynamically rewrite ids while importing contents from one site into another, or when synchronizing two WordPresses.