Update travis config to track coverage properly in jruby

* Update latest bundler to install and exclude unnecessary gems
  from the gemfile

.travis.yml

@@ -1,17 +1,22 @@
 language: ruby
-script: 'bundle exec rake ci'
+before_install: gem install bundler
+bundler_args: --without yard guard benchmarks
+script: "bundle exec rake ci"
 rvm:
   - 1.9.3
   - 2.0.0
   - ruby-head
   - rbx-19mode
-  - ruby-head
-  - jruby-19mode
 matrix:
+  include:
+    - rvm: jruby-19mode
+      env: JRUBY_OPTS="$JRUBY_OPTS --debug"
+    - rvm: jruby-head
+      env: JRUBY_OPTS="$JRUBY_OPTS --debug"
   allow_failures:
-    - rvm: jruby-19mode # No fork(2) support, workaround planned
-    - rvm: ruby-head # Broken at this time, bundler issue on travis
-    - rvm: rbx-19mode # Broken at this time, yard/yardstick issue
+    - rvm: ruby-head     # Broken at this time, bundler issue on travis
+    - rvm: rbx-19mode    # Broken at this time, yard/yardstick issue
+    - rvm: jruby-19mode  # No fork(2) support, workaround planned
 notifications:
   irc:
     channels: