Added make lint-changed which lints changed files only.

scripts/lint-changed.sh

@@ -0,0 +1,6 @@
+#!/bin/bash
+
+MD_FILES=`git diff --cached --name-only | tr " " "\n" | egrep ^.*\.md$`
+
+# Execute Markdown lint if any markdown files have been changed and added to git
+[[ -z "$MD_FILES" ]] || GEM_PATH=.gem .gem/bin/mdl "$MD_FILES"

scripts/pre-commit

@@ -2,3 +2,4 @@
 
 make index
 git add ./pages/index.json
+make lint-changed