Add slather gem

.travis.yml

+before_install: ./ci/before_install.sh
+bundler_args: --without documentation --without development --deployment --jobs=3 --retry=3
 osx_image: xcode7.2
 language: objective-c
 script: ./ci/script.sh

Gemfile

 source 'https://rubygems.org'
 gem 'cocoapods'
+gem 'slather',
+  :git      => "https://github.com/venmo/slather",
+  :branch   => "master"
 gem 'xcpretty'
 gem 'xcpretty-travis-formatter'

Gemfile.lock

+GIT
+  remote: https://github.com/venmo/slather
+  revision: 7a0921b2470b32839e1e2085305d7088b977f6c1
+  branch: master
+  specs:
+    slather (1.8.3)
+      clamp (~> 0.6)
+      nokogiri (~> 1.6.3)
+      xcodeproj (~> 0.28.2)
+
 GEM
   remote: https://rubygems.org/
   specs:
@@ -8,6 +18,7 @@ GEM
       thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
     claide (0.9.1)
+    clamp (0.6.5)
     cocoapods (0.39.0)
       activesupport (>= 4.0.2)
       claide (~> 0.9.1)
@@ -41,10 +52,13 @@ GEM
     fuzzy_match (2.0.4)
     i18n (0.7.0)
     json (1.8.3)
+    mini_portile2 (2.0.0)
     minitest (5.8.3)
     molinillo (0.4.1)
     nap (1.0.0)
     netrc (0.7.8)
+    nokogiri (1.6.7.2)
+      mini_portile2 (~> 2.0.0.rc2)
     rouge (1.10.1)
     thread_safe (0.3.5)
     tzinfo (1.2.2)
@@ -63,6 +77,7 @@ PLATFORMS
 DEPENDENCIES
   cocoapods
+  slather!
   xcpretty
   xcpretty-travis-formatter

ci/before_install.sh

+#!/usr/bin/env bash
+
+bundle config build.nokogiri --use-system-libraries