travis test matrix includes rvm 2.0.0 when puppet >= 3.2

Puppet 3.2 and higher are supported on Ruby 2.x according to
http://docs.puppetlabs.com/guides/platforms.html#ruby-versions
so it makes sense to test this module on the same matrix.

Exclude older versions of Puppet from the test matrix
under rvm 2.0.0 because older versions of Puppet definitely
fail on rvm 2.0.0.

.travis.yml

@@ -5,6 +5,7 @@ before_install: rm Gemfile.lock || true
 rvm:
   - 1.8.7
   - 1.9.3
+  - 2.0.0
 script: bundle exec rake test
 env:
   - PUPPET_VERSION="~> 2.7.0"
@@ -12,3 +13,9 @@ env:
   - PUPPET_VERSION="~> 3.2.0"
   - PUPPET_VERSION="~> 3.3.0"
   - PUPPET_VERSION="~> 3.4.0"
+matrix:
+  exclude:
+  - rvm: 2.0.0
+    env: PUPPET_VERSION="~> 2.7.0"
+  - rvm: 2.0.0
+    env: PUPPET_VERSION="~> 3.1.0"

CONTRIBUTING.md

@@ -21,11 +21,24 @@ will likely make it into a release a little quicker.
 
 ## Dependencies
 
-The testing and development tools have a bunch of dependencies. You can
-install them using [bundler](http://bundler.io/) like so:
+The testing and development tools have a bunch of dependencies,
+all managed by [bundler](http://bundler.io/) according to the
+[Puppet support matrix](http://docs.puppetlabs.com/guides/platforms.html#ruby-versions).
+By default the tests use a baseline version of Puppet.
+
+If you have Ruby 2.x or want a specific version of Puppet,
+you must set an environment variable such as:
+
+    export PUPPET_VERSION="~> 3.2.0"
+
+Install the dependencies like so...
 
     bundle install
 
+...or promote reuse of bundled gems across projects by running:
+
+    bundle install --path=~/.bundle
+
 ## Syntax and style
 
 The test suite will run [Puppet Lint](http://puppet-lint.com/) and