Try caching maven deps for travis

Author: cowtowncoder

.travis.yml

@@ -10,6 +10,11 @@ jdk:
   - openjdk8
   - oraclejdk11
 
+# 2019-11-26, tatu: Let's try caching Maven dependencies
+cache:
+  directories:
+    - $HOME/.m2
+
 # Below this line is configuration for deploying to the Sonatype OSS repo
 # https://knowm.org/configure-travis-ci-to-deploy-snapshots/
 before_install: "git clone -b travis `git config --get remote.origin.url` target/travis"