Merge pull request #204 from lordofthejars/master

resolves issue #198 by adding Ruby 2 compat mode.
Merge pull request #205 from lordofthejars/master

resolves issue #191 by renaming render method to convert method in Abstr...
[maven-release-plugin] prepare release asciidoctorj-1.5.1
[maven-release-plugin] prepare for next development iteration
Merge pull request #208 from lordofthejars/master

Prepare pom.xml for release of Asciidoctorj 1.5.1
upgraded JRuby, libraries, Maven plugins and RubyGems; fixed upstream test script

- upgraded JRuby to 1.7.16.1
- upgraded Maven plugins
- upgraded libraries (slf4j, jcommander, guava, jsoup)
- upgraded dependent gems (haml, tilt, slim)
- fixed upstream test script
resolves #219 upgrade to Asciidoctor 1.5.2
resolves #202 add oraclejdk8 to Travis CI builds

- add oraclejdk8 to Travis CI builds
- reduce JVM memory settings
Merge pull request #214 from mojavelinux/jruby-upgrade

upgrade JRuby version to 1.7.16.1
resolves #192 Use classpath-relative files in test suite

- Create helper for resolving test files from classpath
- Added JUnit rule to resolve files relative to classpath
use ClasspathResources to resolve paths for cli tests
add slf4j-simple to test runtime
use modern fork settings for surefire
resolves #194 migrate project to multi-module Gradle build

- add multi-module Gradle build
- remove Maven build script (pom.xml)
- setup Gradle wrapper
- relocate core to asciidoctorj-core subproject
- setup asciidoctorj-epub3, asciidoctorj-pdf and asciidoctorj-distribution subprojects
- move bundling of asciidoctorj-epub3 into separate jar
- define version and properName properties for each artifact in gradle.properties
- use JRuby Gradle plugin to manage gems
- bundle only essential sources from gems; copy to output folder of main source set
- configure Gradle to generate Eclipse and IDEA project files
- create distribution zip for AsciidoctorJ (bundles core, epub3 and pdf)
- use Gradle to generate start scripts for distribution
- optimize JVM flags for start scripts in distribution
- add additional information to manifest of artifacts
- configure install to local Maven repository
- configure signing (GPG) plugin
- configure upload to Bintray (creates package & version; includes distribution zip)
- update script to test against Asciidoctor upstream (using Maven to install gem)
- activate and fix broken iconfont test
- autoload asciidoctor-pdf gem when backend is set to pdf
sync README content with website; add info about Gradle build

- sync content from website
- add information about Gradle build
- explain how to perform a release
Merge pull request #222 from mojavelinux/issue-194

resolves #194 migrate project to multi-module Gradle build
update project layout in README
update information about the Gradle assemble task
add sections for IntelliJ IDEA and Eclipse in README [ci skip]
update not about source compliance warning