Update .travis.yml

had to update travis config since it doesn't use go get -t, so it doesn't get dependencies that only exist in test files.

Author: natefinch

.travis.yml

@@ -1 +1,3 @@
-language: go
+language: go
+
+install:  go get -d -t -v github.com/natefinch/lumberjack