travis: separate test runs for verbose and race.

The debug printout in the -race tests interferes with timing, so it
makes race conditions less likely to appear.

.travis.yml

@@ -21,7 +21,9 @@ before_install:
   - sudo chown root:$USER /etc/fuse.conf
 
 install:
+  - go get -t ./...
   - go get -t -race ./...
 
 script:
-  - go test -v -race ./...
+  - go test -v ./...
+  - go test -race ./...