Move duplicative user info above tabs in Django admin

[toolness]

Now that we have user tabs in #2049, it would be nice to move all the common info (email/phone/language/etc) from being "read only" just under the tab to being part of the change template just above the tabs. This will also reduce potential confusion, since it's assumed that what's under the tab is info specific to that tab, not general user info (well except for the general tab).