implement rubocop code edits

lib/smtpapi.rb

@@ -113,6 +113,26 @@ def set_ip_pool(pool_name)
       self
     end
 
+    def json_string
+      escape_unicode(to_array.to_json)
+    end
+    alias_method :to_json, :json_string
+
+    def escape_unicode(str)
+      str.unpack('U*').map do |i|
+        if i > 65_535
+          "\\u#{format('%04x', ((i - 0x10000) / 0x400 + 0xD800))}" \
+          "\\u#{format('%04x', ((i - 0x10000) % 0x400 + 0xDC00))}"
+        elsif i > 127
+          "\\u#{format('%04x', i)}"
+        else
+          i.chr('UTF-8')
+        end
+      end.join
+    end
+
+    protected
+
     def to_array
       data = {}
       data['to'] = @to unless @to.empty?
@@ -134,25 +154,5 @@ def to_array
 
       data
     end
-
-    protected :to_array
-
-    def json_string
-      escape_unicode(to_array.to_json)
-    end
-    alias_method :to_json, :json_string
-
-    def escape_unicode(str)
-      str.unpack('U*').map do |i|
-        if i > 65_535
-          "\\u#{format('%04x', ((i - 0x10000) / 0x400 + 0xD800))}" \
-          "\\u#{format('%04x', ((i - 0x10000) % 0x400 + 0xDC00))}"
-        elsif i > 127
-          "\\u#{format('%04x', i)}"
-        else
-          i.chr('UTF-8')
-        end
-      end.join
-    end
   end
 end

smtpapi.gemspec

@@ -13,8 +13,8 @@ Gem::Specification.new do |spec|
   spec.license       = 'MIT'
 
   spec.files         = `git ls-files -z`.split("\x0")
-  spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
-  spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
+  spec.executables   = spec.files.grep(/^bin/) { |f| File.basename(f) }
+  spec.test_files    = spec.files.grep(/^(test|spec|features)/)
   spec.require_paths = ['lib']
 
   spec.add_development_dependency 'bundler', '~> 1.5'