(GH-170) Prepare for 0.21.0 release

This commit updates the changelog and version for the 0.21.0 release.

This commit also updates the Travis CI link to go to Travis instead of the image.

Author: glennsarti

CHANGELOG.md

@@ -6,6 +6,22 @@ Check [Keep a Changelog](http://keepachangelog.com/) for recommendations on how
 
 ## Unreleased
 
+## 0.21.0 - 2019-08-26
+
+### Added
+
+- ([GH-144](https://github.com/lingua-pupuli/puppet-editor-services/issues/144)) Add a Signature Helper Provider
+- ([GH-163](https://github.com/lingua-pupuli/puppet-editor-services/issues/163)) Add aggregate sidecar tasks
+
+### Fixed
+
+- ([GH-55](https://github.com/lingua-pupuli/puppet-editor-services/issues/55)) Debug Server is now supported on Puppet 6
+
+### Changed
+
+- ([GH-106](https://github.com/lingua-pupuli/puppet-editor-services/issues/106)) Update puppet-lint to 2.3.6
+- ([GH-167](https://github.com/lingua-pupuli/puppet-editor-services/issues/167)) Refactor Language Server inmemory caching
+
 ## 0.20.0 - 2019-07-16
 
 ### Added

README.md

@@ -1,4 +1,4 @@
-[![Appveyor Build status](https://ci.appveyor.com/api/projects/status/arryulh580j47u26?svg=true)](https://ci.appveyor.com/project/lingua-pupuli/puppet-editor-services) [![Travis Build Status](https://travis-ci.com/lingua-pupuli/puppet-editor-services.svg?branch=master)](https://travis-ci.com/lingua-pupuli/puppet-editor-services.svg?branch=master)
+[![Appveyor Build status](https://ci.appveyor.com/api/projects/status/arryulh580j47u26?svg=true)](https://ci.appveyor.com/project/lingua-pupuli/puppet-editor-services) [![Travis Build Status](https://travis-ci.com/lingua-pupuli/puppet-editor-services.svg?branch=master)](https://travis-ci.com/lingua-pupuli/puppet-editor-services)
 
 # Puppet Editor Services
 

lib/puppet-editor-services/version.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 module PuppetEditorServices
-  PUPPETEDITORSERVICESVERSION = '0.20.0' unless defined? PUPPETEDITORSERVICESVERSION
+  PUPPETEDITORSERVICESVERSION = '0.21.0' unless defined? PUPPETEDITORSERVICESVERSION
 
   # @api public
   #