Moving Multisite to it's Own Line in the System Status

I moved the Multisite system status information from the WordPress version line to it's own line.

I actually had no idea that we displayed information about multisite until I wondered why there were two `WP`s in `WP Version` row:
http://cld.wthms.co/RJQf

To make this easier for everyone (devs, and regular users as well) I thought it would be a good idea to move this information onto it's own line to make it immediately obvious what it is. I removed the information from the `WP Version` row and added a row right beneath it:
http://cld.wthms.co/r4uf

If you do have multisite enabled it will look like this:
http://cld.wthms.co/h05j