Redoing upstream code check logic. Adding additional language for missing environments.

[erik-pantheon]

Redoing upstream code check logic. Adding additional language for missing environments. The current code returns a positive on the updates check even if the site is up to date with the upstream.

[mikevanwinkle]

When I test this it says dev hasn't been created. I think that's because you should replace !empty() with isset(). If the
if $upstream->test->is_up_to_date_with_upstream is set to false then !empty($upstream->test->is_up_to_date_with_upstream) returns false, while isset($upstream->test->is_up_to_date_with_upstream) would return true.

```+-------------+------------------------------+
| Environment | Status                       |
+-------------+------------------------------+
| dev         | Environment not created yet. |
| test        | Environment not created yet. |
| live        | Environment not created yet. |
+-------------+------------------------------+```

[erik-pantheon]

'k. isset() wasn't returning properly when I ran it on my local, so I swapped to the !empty. Let me give that another go. Thanks! - E

[erik-pantheon]

@mikevanwinkle Updated code to reflect the [behind] value return and lack of API return for Test and Live environments.

[mikevanwinkle]

👍