Update .travis.yml (#324)

Adding power support.
diff --git a/.travis.yml b/.travis.yml
index 0ececa0..1e0fa4c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,3 +1,6 @@
+arch:
+  - amd64
+  - ppc64le
 language: go
 
 go: