Merge pull request #205 from Code-dot-mil/travis-ci

Simplify .travis.yml

Author: Ari Chivukula

.travis.yml

@@ -1,10 +1,5 @@
-dist: trusty
-sudo: false
 language: ruby
 cache: bundler
-env:
-  global:
-  - NOKOGIRI_USE_SYSTEM_LIBRARIES=true
 before_install:
 - gem update --system
 - gem install bundler