Allow failures in 1.4.x because of etcd problem

The error seen is:

req.Cancel undefined
(type *http.Request has no field or method Cancel)

And is possibly the result of something etcd folks changed. Sadly, the
fast building 1.4.x won't work at the moment :(

.travis.yml

@@ -11,6 +11,7 @@ script: 'make test'
 matrix:
   allow_failures:
     - go: tip
+    - go: 1.4.3
 notifications:
   irc:
     channels: