Update the regions with private networking in Digital Ocean
Merge pull request #501 from manevski/master

Update the regions with private networking in Digital Ocean
Print an error if trying to mount a volume that is mounted under a different device in /etc/fstab.

Fixes #497: bash -l /tmp/setup_volume fail silently.
Merge branch 'master' of github.com:rubber/rubber
We don't need the optional ElasticSearch configuration file for graylog2, so comment out the option.

Fixes #498: rubber:graylog:server:create_inputs fails
Dupe the version string in the gemspec so a mutable copy is made.

We freeze the version string because it's supposed to be constant.  Older versions of RubyGems, such as the ones that ship with Ruby 1.9.3, expect to be able to modify the version string, however.  Generally the gemspec ships as part of the gem with the value resolved, so this isn't an issue.  But if bundler is using a git or local copy, where the version directly references our constant, its inability to modify the version results in a load error.

Fixes #453: Is VERSION.freeze needed?
Upgraded Passenger (Apache) from 3.0.19 to 4.0.48.
Locked the Passenger (nginx) version down via config.
There's no need to make this configurable since it's hard-coded in the Passenger installation packages.
Use the newer Passenger 4 configuration name.
Set the Passenger (nginx) group just like we do for Apache.
Make sure we load files in lexicographic order.
Reduced shared_buffers size in PostgreSQL so it'll work out of the box on a 512 MB DigitalOcean droplet.
Preparing the 2.11.0 release.
Added a way to retrieve the OS version for an instance.
Added a way of specifying packages to be installed by OS version.
Omit the @os_version and @capistrano ivars when converting an InstanceItem to a hash.