Merge pull request #1867 from jochenberger/add-travis-cache

cache the content of the local Maven repository between builds

.travis.yml

@@ -212,3 +212,7 @@ before_script:
 script:
   # Pick one test in this directory and verify
   - time ./toolset/run-ci.py verify "$TESTDIR"
+
+cache:
+  directories:
+  - /home/testrunner/.m2/repository