Use a different crate name in a test to prevent deadlocks

This test does a lot of different manipulations of categories and crate
categories and it was using a crate named foo. The good_categories test
also used a crate named foo, and these two tests were causing a postgres
deadlock.

I was able to cause deadlocks more often by duplicating the update_crate
test and the good_categories test:

https://travis-ci.org/integer32llc/crates.io/builds/187302718

Making this change and running the duplicated tests resulted in 0
deadlocks:

https://travis-ci.org/integer32llc/crates.io/builds/187306433

This is unlikely to happen in production; requests get a database
connection that gets closed when the request finishes, and the publish
request only modifies the categories once, not as much as the
update_crate test is. It seems unlikely that two people would publish
the same crate at exactly the same time.

src/tests/category.rs

@@ -74,7 +74,7 @@ fn update_crate() {
         ::json::<GoodCategory>(&mut response).category.crates_cnt as usize
     };
     ::mock_user(&mut req, ::user("foo"));
-    let (krate, _) = ::mock_crate(&mut req, ::krate("foo"));
+    let (krate, _) = ::mock_crate(&mut req, ::krate("foocat"));
     ::mock_category(&mut req, "cat1", "cat1");
     ::mock_category(&mut req, "Category 2", "category-2");