Missing i18n on site admin screens

[johnbillion]

r33186 introduced some strings which aren't internationalised.

[johnbillion]

33317.patch​ also corrects the trailing slash which is missing from the get_home_url() calls.

[ocean90]

We have the same strings internationalized in trunk/src/wp-admin/my-sites.php@33442#L110​, so no new strings here.

33317.patch​ looks good. (Note: my-sites.php (and probably others) also doesn't use the trailing slash.)

[helen]

In 33603:

Network admin: Internationalize some existing strings that were missed in [33186].

Also adds the trailing slash to the get_home_url() calls.

props johnbillion.
fixes #33317.