Improve changelog using keepachangelog format

CHANGELOG.md

@@ -1,38 +1,49 @@
-### 0.9 - 2017-06-15
+# Changelog
+All notable changes to this project will be documented in this file.
 
-* New features
-  * Budgets
-  * Basic polls
-  * Collaborative legistlation
-  * Custom pages
-  * GraphQL API
-  * Improved admin section
-* Enhancements
-  * Improved admin section
-  * Rails 4.2.8
-  * Ruby 2.3.2
-* Bug fixes
-  * CKEditor locale compilation fixed
-  * Fixed bugs in mobile layouts
-* Deprecations
-  * SpendingProposals are deprecated now in favor of Budgets
+The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
+and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
-### 0.8 - 2016-07-21
+## [Unreleased]
 
-* New features
-  * Support for customization schema, vía specific custom files, assets and folders
-* Enhancements
-  * Rails 2.4.7
-  * Ruby 2.3.1
-* Bug fixes
-  * Fixed bug causing errors on user deletion
+## [0.9.0] - 2017-06-15
+### Added
+- Budgets
+- Basic polls
+- Collaborative legistlation
+- Custom pages
+- GraphQL API
+- Improved admin section
 
-### 0.7 - 2016-04-25
+### Changed
+- Improved admin section
+- Rails 4.2.8
+- Ruby 2.3.2
 
-* New features
-  * Debates
-  * Proposals
-  * Basic Spending Proposals
-* Enhancements
-  * Rails 2.4.6
-  * Ruby 2.2.3
+### Deprecated
+- SpendingProposals are deprecated now in favor of Budgets
+
+### Fixed
+- CKEditor locale compilation fixed
+- Fixed bugs in mobile layouts
+
+## [0.8.0] - 2016-07-21
+### Added
+- Support for customization schema, vía specific custom files, assets and folders
+
+### Changed
+- Rails 4.2.7
+- Ruby 2.3.1
+
+### Fixed
+- Fixed bug causing errors on user deletion
+
+## [0.7.0] - 2016-04-25
+### Added
+- Debates
+- Proposals
+- Basic Spending Proposals
+
+### Changed
+- Rails 4.2.6
+- Ruby 2.2.3