Add caching to the travis ci config to speed things up

cnsumner · cnsumner · commit 7bb339952d77 · 2018-10-05T01:39:45.000-04:00
diff --git a/.travis.yml b/.travis.yml
@@ -14,4 +14,8 @@ notifications:
     on_success: never
 branches:
   only:
-    - master
+    - master
+cache:
+  cargo: true
+  directories:
+    - target
