Travis: Split into primary/secondary groups

Secondary template engines will not break the build.

.travis.yml

@@ -4,17 +4,21 @@ rvm:
   - 1.8.7
   - 1.9.2
   - 1.9.3
-  - 2.0.0
+  - 2.0
   - 2.1
   - 2.2
   - ruby-head
   - jruby-18mode
   - jruby-19mode
   - rbx
+env:
+  - BUNDLE_WITHOUT=secondary
+  - BUNDLE_WITHOUT=primary
 
 matrix:
   include:
     - rvm: 1.9.3
       env: RDOC_VERSION="~>3.0"
   allow_failures:
     - rvm: rbx
+    - env: BUNDLE_WITHOUT=primary

Gemfile

@@ -3,27 +3,29 @@ source 'https://rubygems.org'
 gem 'yard', '~> 0.8.6'
 gem 'ronn', '~> 0.7.3'
 gem 'minitest', '~> 5.0'
+gem 'contest'
 
 gem 'rake'
 
-group :engines do
-  gem 'execjs', '~> 2.0.0'
-  gem 'asciidoctor', '>= 0.1.0'
+group :primary do
   gem 'builder'
-  gem 'coffee-script'
-  gem 'contest'
-  gem 'creole'
   gem 'erubis'
   gem 'haml', '>= 2.2.11', '< 4'
-  gem 'kramdown'
   gem 'less'
-  gem 'liquid'
+  gem 'coffee-script'
   gem 'markaby'
-  gem 'maruku'
-  gem 'nokogiri' if RUBY_VERSION > '1.9.2'
-  gem 'radius'
   gem 'sass'
+end
+
+group :secondary do
+  gem 'creole'
+  gem 'kramdown'
   gem 'rdoc', (ENV['RDOC_VERSION'] || '> 0')
+  gem 'radius'
+  gem 'asciidoctor', '>= 0.1.0'
+  gem 'liquid'
+  gem 'maruku'
+  gem 'nokogiri' if RUBY_VERSION > '1.9.2'
 
   platform :ruby do
     gem 'wikicloth'