Updated ruby-head
Update run_list for standard VM

- PostgreSQL recipe name has changed
- MySQL client recipe is included by server recipe
- No more needed to override PostgreSQL max_connections attribute
- No need to override MySQL server_root_password attribute
New names for Maven cookbook and Redis recipe

Related to:
- travis-ci/travis-cookbooks#229
- travis-ci/travis-cookbooks#211
Merge pull request #4 from gildegoma/update-recipes-and-attributes

Update run_list for standard VM
Merge branch 'master' of https://github.com/travis-ci/travis-images
remove ruby-head and jruby-head
change the provisioner to use chef installer
update node 0.10.18 => .20
add 0.10.18 to the installed node versions
remove chef gem from installed gems
use maven and not maven3
Update Ruby and JVM workers to new java cookbook

Related to travis-ci/travis-cookbooks#236
Add Oracle JDK 8 to Ruby VM
update the default 0.10 version, and add 0.8.26 for a customer
add lib event and md5deep
Merge pull request #5 from gildegoma/new-java-recipe

Update Ruby and JVM workers to new java cookbook
Provision with Chef version 11.8.0