caching in travis image build

Johan Brichau · Johan Brichau · commit 8779a7226c11 · 2016-03-26T16:12:55.000+01:00
diff --git a/.travis.yml b/.travis.yml
@@ -9,3 +9,6 @@ smalltalk:
   - GemStone-3.1.0.6
   - GemStone-3.2.12
   - GemStone-3.3.0
+cache:
+  directories:
+    - $SMALLTALK_CI_CACHE
