Add race and vet testing.

.travis.yml

@@ -3,6 +3,10 @@ go:
     - 1.4
     - 1.5
     - 1.6
+before_script:
+    - go vet ./..
+gobuild_args:
+    - -race
 install:
-      - go get github.com/bwmarrin/discordgo
-      - go get -v .
+    - go get github.com/bwmarrin/discordgo
+    - go get -v .