Add cache setting to Travis

.travis.yml

@@ -1,3 +1,20 @@
+# Use Docker-based container (instead of OpenVZ)
+sudo: false
+
+cache:
+  directories:
+    - $HOME/.ivy2/cache
+
+    # At the moment, sbt 0.13.5 is preinstalled in Travis VM image,
+    # which fortunately corresponds to current scalaz settings.
+    # The line below can be used to cache a given sbt version.
+    # - $HOME/.sbt/launchers/0.13.x
+
+    # The line below is used to cache the scala version used by the build
+    # job, as these versions might be replaced after a Travis CI build
+    # environment upgrade (e.g. scala 2.11.2 could be replaced by scala 2.11.4).
+    - $HOME/.sbt/boot/scala-$TRAVIS_SCALA_VERSION
+
 language: scala
 
 # TODO - we'd like to actually test everything, but the process library has a deadlock right now
@@ -5,8 +22,6 @@ jdk:
   - openjdk6
 #  - oraclejdk7
 
-sudo: false
-
 env:
   global:
     - JVM_OPTS="-Xms1024m -Xmx1024m -XX:ReservedCodeCacheSize=128m -XX:MaxPermSize=256m"
@@ -32,10 +47,14 @@ env:
     - SCRIPTED_TEST="safeUnitTests"
     - SCRIPTED_TEST="checkBuildScala211"
 
+notifications:
+  email:
+    - eugene.yokota@typesafe.com
+    - joshua.suereth@typesafe.com
+
 script:
   - sbt "$SCRIPTED_TEST"
 
-notifications:
-  email:
-    - qbranch@typesafe.com
-
+  # Tricks to avoid unnecessary cache updates
+  - find $HOME/.sbt -name "*.lock" | xargs rm
+  - find $HOME/.ivy2 -name "ivydata-*.properties" | xargs rm