Proof the site with CircleCI.

Gemfile

@@ -32,3 +32,7 @@ if ENV['BENCHMARK']
   gem 'rbtrace'
   gem 'stackprof'
 end
+
+if ENV['PROOF']
+  gem 'html-proofer', '~> 2.0'
+end

circle.yml

@@ -0,0 +1,9 @@
+machine:
+  timezone: UTC
+  ruby:
+    version: 2.1.5
+  environment:
+    PROOF: true
+test:
+  override:
+    - script/proof -f

script/proof

@@ -5,20 +5,24 @@
 
 set -e
 
-if [[ "$1" != "-f" ]]; then
-  git diff --name-only ..master | grep '^site/' || {
-    echo "No site files changed. We'll skip proofing. Run with -f to force."
-    exit 0
-  }
-fi
-
-echo "Some site files have been changed! Proofing..."
-
-command -v htmlproof || {
-    echo "Installing HTML::Proofer!"
-    gem install html-proofer -- --use-system-libraries
+function msg {
+	printf "\e[0;37m==> $1\e[0m\n"
 }
 
-bundle exec jekyll build -s site -d _site --trace
-printf "\e[0;36mProofing begins now!\e[0m\n"
-htmlproof ./_site
+SOURCE="site"
+DESTINATION="_site"
+
+export PROOF=true
+export NOKOGIRI_USE_SYSTEM_LIBRARIES=true
+
+# 1.
+msg "Installing..."
+bundle install -j8 > /dev/null || bundle install > /dev/null
+
+# 2.
+msg "Building..."
+bundle exec jekyll build -s $SOURCE -d $DESTINATION --full-rebuild --trace
+
+# 3.
+msg "Proofing..."
+bundle exec htmlproof ./$DESTINATION --href-ignore /Chrononaut/,/twitter.com/