Remove go 1.4.3

It apparently requires a vet install that other versions don't.  If
1.3.3 works, then we can assume 1.4.3 is OK.
diff --git a/.travis.yml b/.travis.yml
index 7ea0357..ffa8740 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,7 +2,6 @@
 language: go
 go:
   - 1.3.3
-  - 1.4.3
   - 1.5.4
   - 1.6.2
   - tip