Add encoding to ruby files

Rakefile

@@ -1,4 +1,7 @@
+# encoding: utf-8
+
 require 'devtools'
+
 Devtools.init_rake_tasks
 
 Rake.application.load_imports

bin/mutant

@@ -1,5 +1,7 @@
 #!/usr/bin/env ruby
 
+# encoding: utf-8
+
 trap('INT') do |status|
   exit! 128 + status
 end