Add missing encoding tags

lib/mutant/cli/builder.rb

@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class CLI
     # Abstract base class for strategy builders

lib/mutant/matcher/filter.rb

@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   class Matcher
     # Matcher filter

lib/mutant/predicate.rb

@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 module Mutant
   # Abstract base class for predicates used to filter subjects / mutations
   class Predicate

spec/unit/mutant/cli/builder/rspec_spec.rb

@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::CLI::Builder::Rspec do

spec/unit/mutant/matcher/filter_spec.rb

@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 describe Mutant::Matcher::Filter do

spec/unit/mutant/predicate_spec.rb

@@ -1,3 +1,5 @@
+# encoding: utf-8
+
 require 'spec_helper'
 
 filter_helpers = proc do