Standardize travis.yml on pattern introduced in stdlib

.gemfile

@@ -1,5 +0,0 @@
-source :rubygems
-
-puppetversion = ENV.key?('PUPPET_VERSION') ? "= #{ENV['PUPPET_VERSION']}" : ['>= 2.7']
-gem 'puppet', puppetversion
-gem 'puppetlabs_spec_helper', '>= 0.1.0'

.gitignore

@@ -1,2 +1,3 @@
 *.swp
 pkg/
+Gemfile.lock

.travis.yml

@@ -1,26 +1,25 @@
 language: ruby
+bundler_args: --without development
+script: "bundle exec rake spec SPEC_OPTS='--format documentation'"
 rvm:
   - 1.8.7
   - 1.9.3
-before_script:
-after_script:
-script: "rake spec"
+  - ruby-head
 env:
-  - PUPPET_VERSION=3.0.2
-  - PUPPET_VERSION=2.7.20
-  - PUPPET_VERSION=2.7.6
-  - PUPPET_VERSION=2.6.9
+  - PUPPET_GEM_VERSION="~> 2.6"
+  - PUPPET_GEM_VERSION="~> 2.7"
+  - PUPPET_GEM_VERSION="~> 3.0"
 matrix:
- exclude:
-  - rvm: 1.9.3
-    gemfile: .gemfile
-    env: PUPPET_VERSION=2.6.9
-  - rvm: 1.9.3
-    gemfile: .gemfile
-    env: PUPPET_VERSION=2.7.6
-  - rvm: 1.9.3
-    gemfile: .gemfile
-    env: PUPPET_VERSION=2.7.20
+  allow_failures:
+    - rvm: ruby-head
+  exclude:
+    - rvm: 1.9.3
+      env: PUPPET_GEM_VERSION="~> 2.7"
+    - rvm: ruby-head
+      env: PUPPET_GEM_VERSION="~> 2.7"
+    - rvm: 1.9.3
+      env: PUPPET_GEM_VERSION="~> 2.6"
+    - rvm: ruby-head
+      env: PUPPET_GEM_VERSION="~> 2.6"
 notifications:
   email: false
-gemfile: .gemfile

Gemfile

@@ -0,0 +1,13 @@
+source :rubygems
+
+group :development, :test do
+  gem 'puppetlabs_spec_helper', :require => false
+end
+
+if puppetversion = ENV['PUPPET_GEM_VERSION']
+  gem 'puppet', puppetversion, :require => false
+else
+  gem 'puppet', :require => false
+end
+
+# vim:ft=ruby