The installer does not translate profile names and descriptions

In a detailed review of the functionality committed in #1260716: Improve language onboarding user experience, Garrett Albright found out that the install profile names and descriptions are not translated in the installer, even though they are in the .po file generated currently by localize.drupal.org. The reason for that is that the profile form was not updated with that patch to st() the profile name and description.

Here is an excerpt from the drupal-7.10-pt-pt.po file downloadable from localize.drupal.org that translates the name and description of the minimal distribution:

msgid "Minimal"
msgstr "Mínimo"
msgid "Start with only a few modules enabled."
msgstr "Começar com apenas alguns módulos activos."

To make these actually appear on the UI, the attached patch should be applied on top of #1392192: st() still requires profile to be selected before translating (if it is not yet committed). The patch adds the two st() calls to make this happen and some comments to document why is it OK to use st() on dynamic data there.