Travis - add 6.0 build, remove default JRuby 1.7 build, bump RVM versions

Author: jakelandis

.travis.yml

@@ -10,10 +10,12 @@ script:
 - bundle exec rspec spec
 matrix:
   include:
-  - rvm: jruby-9.1.10.0
+  - rvm: jruby-9.1.13.0
     env: LOGSTASH_BRANCH=master
-  - rvm: jruby-9.1.10.0
+  - rvm: jruby-9.1.13.0
     env: LOGSTASH_BRANCH=6.x
-  - rvm: jruby-1.7.25
+  - rvm: jruby-9.1.13.0
+    env: LOGSTASH_BRANCH=6.0
+  - rvm: jruby-1.7.27
     env: LOGSTASH_BRANCH=5.6
-  fast_finish: true
+  fast_finish: true