Use the buck-cache

For many users this won't help, but if anyone uses multiple
versions of Buck, this will make their builds a lot faster.

Author: shs96c

.buckconfig

@@ -11,6 +11,9 @@
       java/client/build, \
       java/server/build
 
+[cache]
+  mode = dir
+
 [test]
   # Maximum timeout of 10 minutes per test (since each suite counts as a test)
   timeout = 600000