Add support for checking YAML validity using Travis CI

tests/yaml.rb

@@ -0,0 +1,21 @@
+#!/usr/bin/env ruby
+require 'yaml';
+$file_count = 0;
+markdown_files = Dir["./**/*.html.markdown"]
+markdown_files.each do |file|
+	begin
+		YAML.load_file(file)
+		$file_count = $file_count + 1
+	rescue Exception => msg
+		puts msg	
+	end
+end
+files_failed = markdown_files.length - $file_count
+if files_failed != 0
+	puts "FAILURE!!! #{files_failed} files were unable to be parsed!"
+	puts "Please check the YAML headers for the documents that failed!"
+	exit 1
+else
+	puts "Success. All #{$file_count} were checked"
+	exit 0
+end