WordPress xmlrpc wp_getPosts filter for slug

[SunWaves]

When using the Wordpress xmlrpc, it is sometimes very useful to get posts based off of slugs rather than post id.

A use case for this would be synchronizing or migrating two Wordpress sites with the same posts, but with different databases and post ID's.

[SunWaves]

The patch enables an extra optional argument of 'name' to the xmlrpc getPosts method which will allow xmlrpc users to getPosts by slug name

[markoheijnen]

First if statement still using spaces instead of tabs. Also no clue if name also works for pages (pagename).

Also for syncing even the slug isn't save since slug can also not be the same. I'm not sure if we should include it or not.