[#6] CHANGELOG synchronization with GH release notes

Using Chandler.

.travis.yml

@@ -10,6 +10,11 @@ before_install:
  - "export TRAVIS_COMMIT_MSG=$(git log --format=%B -n 1 $TRAVIS_COMMIT)"
  - git config user.email "szpak-ci@users.noreply.github.com"
  - git config user.name "Szpak CI Bot"
+ # Chandler for release notes synchronization
+ - ruby --version
+ - rvm install 2.4.1
+ - ruby --version
+ - gem install chandler
 
 install: true
 script:
@@ -24,6 +29,7 @@ cache:
   directories:
     - $HOME/.gradle/caches/
     - $HOME/.gradle/wrapper/
+    - $HOME/.rvm/
 
 env:
   global:

build.gradle

@@ -128,3 +128,17 @@ if (hasProperty('pluginPortal')) {
     }
     ciBuild.dependsOn publishPlugins
 }
+
+if (hasProperty('changelogSync')) {
+
+    task syncChangelog(type: Exec) {
+        doFirst { logger.info("Synchronizing changelog with GitHub for version ${project.version}") }
+        commandLine 'chandler', 'push', "release/${project.version}", '--tag-prefix=release/'
+    }
+
+    syncChangelog {
+        onlyIf { ciBuild.isInReleaseMode }
+        mustRunAfter releaseRepository, publishPlugins
+    }
+    ciBuild.dependsOn syncChangelog
+}